While I dislike like everybody else having to go through the airports' "security theater", I don't get the logic behind the continuous lamentations claiming that these measures do nothing except inconveniencing people and wasting money.
What is the rationale behind this idea ? Is it based on claims by some influential person ? Or on some statistics ?
Is that idea based on the thought that they confiscate objects that can hardly be used to harm a flight ?
World leaders, at least in most non-third-world countries, cannot avoid listening to official experts. Are those experts thought to be wrong ? Or are there claims that some lobby, political or economical group or other entities benefits from excessive security measures ?
My answer to why airport security is such has always been that such measures are mostly useful because without them, even small, improvised or wannabe terrorists, or even just psychologically disturbed persons, would know that they can board with small knives, scissors, chemicals and other things that can easily be turned into attack devices. If that kind of people knew they can happily board with that, tragedies would happen unacceptably more often. Considering how common air travel became in the last decades, I would expect a carnage. Compared to cars, buses or trains, this is of course enormously more relevant for flights, as if there is a threat the plane cannot just pull over or brake and deal with the threat or wait for the emergency services to arrive. It either keeps flying under control or people die. The filter is not there to catch attackers, it's there to make them not attack. Are the complaints based on data showing that too few attackers are caught through these measures ?
The Wikipedia page about the "security theater" describes it as measures that are intended to provide the feeling of improved security while doing little or nothing to achieve it, which means that that feeling of security is fake. It also mentions critiques like Many measures are put in place in reaction to past threats and "are ineffective at actually stopping terrorism, as potential attackers can simply change tactics." which to me means "it's useless to try to stop types of attack that happened in the past because attackers can also do attacks of other types", which makes no sense to me unless the success was measured like "either we stop all possible attacks or it doesn't matter how many we stop". So I can't rely on that page to find an answer to my doubt.
Note that my question is not of the type "why do they confiscate small knives and then I was served my inflight meal with a metal fork and kinfe ?". These situations are hopefully exceptions, and anyway the solution wouldn't be stopping confiscating small knives but stopping serving inflight meals with metal knives. I'm not asking about the logic behind finding these situations absurd.
My question is: what is the mainstream reasoning behind the widely shared idea that the current security measures are excessive and not useful ?