most of airport security rests on the notion of going over a series of long tests will elicit unusual (fear, stress) responses from malicious actors and these can then be flagged for even thorougher checks which will then eventually lead to discovery, banning or removal of luggage

so it's not the test accuracy by itself but rather then the fact that these tests are happening at all

You have surprising faith that the system is well designed.

Malicious actors don't get as stressed as normal people who don't want to miss their flight about the long series of obviously pointless tests. Why would they?

And there isn't anyone who surveils the queues and takes the worried looking for further checks. This can happen around immigration checks. It happens for flights to Israel. But not in routine airport security.

This kind of thinking is as legitimate as believing lie detectors work, i.e., not at all.