In Taiwan, what is the penalty for overstaying a tourist visa with legitimate reasons (for example, a flight was cancelled or delayed, or a transportation closure made someone miss getting to the airport in time)? What fines or barriers to future travel would someone face?
Penalties are levied via a fine. The fine ranges from around 1000 NTD (if you overstay by an hour) up to 10000 NTD.
Source (page 5) http://iff.immigration.gov.tw/public/Data/11714474471.pdf
As mentioned by Michael Pryor, there is a fine. Any natural force is still your responsibility, including typhoons. From my understanding, the only way you can overstay your visa is by government mandate (quarantine, jail, etc).
That being said, I have overstayed a visa by 2 days and didn't have to pay anything because there was a typhoon. Really, it is up to the discretion of the immigration officer you meet. Also note, that you can be jailed for up to 2 MONTHS if you overstay. I have never heard of that being used except in the case of a suspected drug smuggler though . Your best bet is to check the weather forecast. If you absolutely can't get out on the last day of your visa, just accept the fact that you will have to pay some cash.
I was charged "Over Stay" even though my visa waver had run out less than 24 Hours. All because I had missed my flight by a few hours!
That was because I checked in on the same day as flight but I should have checked in the night before as my flight was just past midnight. (Slight oversight on my part, not checking the time and date correctly, so my flight had already gone some 22 hours earlier)
So their Immigration told me I was 90+1 Days and I had to pay a penalty charge. Even though it was less than 24 Hours, they hit me a with a hard 2,000 NTD$ (£40) charge.
I guess I was a bit miffed as I was only expecting a small fine, no more than 1000 NTD$ anyway.
I kindly tried to argue that I had already paid 11,200 NTD$ for the change in the flight ticket so I could leave on the next flight in less than a couple of hours.
This fell on deaf ears and after a few minutes I was surrounded by 5 or 6 armed airport security.
I was told that if I refused to pay the fine, I would be arrested and taken to a detention office, where I could be transferred to a jail and would end up paying a lot more before I would be released to be allowed to go home.
Understandably, I backed down and paid the fine so their immigration would give me the necessary paperwork for me to proceed out of there.
If anything, it's taught me a valuable, if not expensive lesson.
Do not miss your flight or stay past the time you are allowed to stay. To say their airport immigration is very strict is an understatement.