Such claims are false but are very common misconceptions held by foreigners who do not know Singapore well.
Rules in Singapore are rarely and only very selectively enforced. This is true for locals, but especially true for foreigners/tourists.
Indeed, in many situations, rules are less often enforced in Singapore than in most rich western countries.
Take the example of drinking water on the MRT.
On paper, there is indeed a rule against this:
Can I eat and drink in trains and stations?
No, it is not permitted. ... a fine of up to $500. ...
Can I take a sip of plain water?
Drinking plain water, or any beverage for that matter, is not permitted because the beverage could spill and wet seats, soil other commuters’ belongings or cause a fellow commuter to slip and fall. Help us prevent any accidents in the network and maintain a clean environment, so that it would be a pleasant ride for all.
But in practice, fines are almost never given for drinking water (or indeed for drinking or eating anything). I (and many others) have been regularly drinking water on the MRT for over 30 years without ever being fined or even told to stop.
It is true that if you happen to be within sight of an MRT staff member, they might tell you to stop. But they certainly won't fine you.
As one writer states:
Eating/drinking on the train seems really more common nowadays (like every 20-30 rides i see it happening).
This time I actually went up to the the person and told them what they are doing is illegal. All I got was very lame and nonchalant excuses like “I’m not spilling anything; the $500 fine won’t be enforced anyway; this is not as serious as some others who….”, as if I was the one being a busybody. ...
Note that today, every car on the train has cameras. Also, every passenger's mode of payment (EZ-Link/debit/credit card or phone) is linked to her identity. So, if the authorities wanted, they could easily, efficiently, and regularly enforce this prohibition against eating and drinking (as they do with for example speeding). But they don't.
In Singapore, rules are rarely enforced. But on the rare occasion that they do get enforced, the punishment may be very harsh and given wide publicity (by the entirely state-controlled media), so as to scare off potential ill-doers.
law enforcement in Singapore operates on the Chinese principle of "Kill the chicken to scare the monkey" (杀鸡儆猴), meaning enforcement is loose ... but punishments are draconian.
Many foreigners have only a passing acquaintance of Singapore (this includes many expats who may have lived in Singapore for many years but dwell mostly in a bubble).
But they will almost certainly have heard of Michael Fay, the chewing gum ban, and the death penalty for drug traffickers.
They then parrot and nourish the common misconceptions that "in Singapore, you should assume all rules are implemented at all times" or "rules which are elsewhere seen as a formality or unimportant are enforced in Singapore. eg, not eating or drinking anything (even water!) on the MRT".
Littering is another famous "example" of how Singapore supposedly strictly enforces its laws.
Again, on paper, there are the usual fines and also the famous Corrective Work Orders where offenders are made to pick up litter while wearing special uniforms (since 2022 pink and fluorescent yellow).
But again, in practice, rules against littering are very rarely enforced.
Foreign tourists or foreign expats living in wealthy neighbourhoods may (incorrectly) believe that littering is rare or non-existent in Singapore because the rules are strictly enforced and most Singaporeans don't litter. (It is true that better educated and richer Singaporeans seldom litter--and these are probably the only Singaporeans that foreign expats have much interaction with.)
But come to any HDB estate (where about 80% of Singaporeans live) and you'll see plenty of litter, especially at heavily frequented areas (coffeeshops, playgrounds, basketball courts, etc.) and especially later in the day.
Why especially later in the day? The reason is that all litter magically disappears early every morning before dawn, thanks to the armies of cheap cleaners (mostly from Bangladesh).
This by the way brings up another common misconception about Singapore: "Singapore is very clean thanks to law-abiding citizens who never litter." This is incorrect. Singapore is very clean despite rampant littering, thanks to the armies of cheap cleaners. If Singapore had as few cleaners as most rich western countries (where low-skilled labor is much more expensive), the mess and stench would become much more noticeable.
Enforcement against littering is more than zero but trivial relative to the scale of the problem: About 27,200 littering tickets were issued per year in 2017-21. I'm certain that less than 1 in 1000 instances of littering are ever punished.
Smoking is a similar problem. On paper, smoking is banned in many areas (including within 5m of any bus stop and schools). But in practice, rules are very rarely enforced and smokers happily puff away even in prohibited areas. (They also then almost always litter their cigarette butts.)
I have repeatedly reported and written to my Members of Parliament and Town Council about littering and smoking problems in my neighbourhood, but nothing is ever done. The same rampant littering and smoking persist year after year.
When Singaporeans travel to rich western countries, they are often surprised by how strictly rules are enforced abroad.
Example: A Singaporean might try to cheat on train fares. She might have a one-week unlimited train travel pass, then cheat by continuing to use it the day after expiry. She does so because in similar situations in Singapore, tourists and foreigners will almost always be treated with kid gloves, given the benefit of doubt, and simply be let off with a warning. So, she is then surprised when the European train conductor actually fines her.
Example: A tour bus driver announces that they will leave the shopping mall at exactly 2pm and will not wait one second for any latecomers. A Singaporean who's then late by a few minutes is then surprised to find that the tour bus driver actually keeps his promise, because in Singapore, in a similar situation, the bus driver would never leave until all his passengers are back.
Foreigners and tourists--especially those from rich (and usually white) countries--are treated with kid gloves. It is only locals who may be treated harshly.
Singapore's rulers have great economic interest in attracting such foreigners and tourists. So, they will NOT suddenly decide to go out of their way and make an example of such foreigners and tourists in cases of minor wrongdoing such as drinking water on the train or littering.
In especially egregious cases of major wrongdoing (such as Michael Fay), they may apply the law. But even then, they may bend the law a little, as was the case with Michael Fay whose caning was reduced from 6 to 4 strokes after appeals by Bill Clinton.
Consider for example the laws against illegal immigration, which mandate that illegal immigrants (including those that simply overstay their visa) shall "be punished with caning with not less than 3 strokes" (before being expelled). In the west, this draconian law should be just as famous (as Michael Fay, chewing gum, and death penalty for drug trafficking).
The reason it isn't more famous in the West is that the law is applied only to persons from poor (and usually "brown") countries in the region (Indonesia, Bangladesh, etc.).
Persons from rich (and usually white) countries are exempt from this law. See especially the case of the US citizen Kamari Kenyada Charlton who overstayed his visa yet was not caned (moreover, he was involved in some shady dealings and scams--he wasn't some law-abiding citizen who just happened to accidentally overstay his visa).
An example of how it is only locals who are treated harshly is the consumption of drugs outside of Singapore:
All Singaporeans / Permanent Residents found to have consumed illegal drugs, EVEN OUTSIDE OF SINGAPORE, can face the penalty of imprisonment of up to 10 years, a fine not exceeding S$20,000 or both.
Note well that this law applies only to Singapore citizens (and permanent residents). Foreigners in Singapore who are found to have consumed drugs outside of Singapore are not subject to any punishment. (It is possible that when attempting to enter Singapore, a foreigner may be drug-tested and denied entry. But she will not be otherwise punished. And she will not be punished once she has entered Singapore.)
Altogether, in Singapore, you need NOT assume all rules are implemented at all times.
Or, at least contrary to the stereotyped misconceptions held by some foreigners, you need NOT go out of your way and make this assumption of Singapore any more than of any other country in the world that you happen to be living in or visiting.
If you are someone who believes in always assuming all rules are implemented at all times everywhere in the world, then go ahead and continue believing that in Singapore.
But if you're not, you need not and should not specially make this assumption in Singapore. Doing so will only make your life/experience in Singapore miserable.
And in particular (and contrary to the quoted claim), you need NOT worry about being punished for eating or drinking on the train (or indeed for any other minor wrongdoing such as littering).