That idea is also a perception of safety. No team of hijackers has attempted to take over a plane post 9/11.
If TSA is just theater, couldn't an attacker simply bring weapons sufficient enough to hold off the crowd and break the door? The hijackers on 93 only had box cutters.
It is the combined perception of airport security and the perception that passengers will fight that deter bad actors from even trying.
It's the cockpit doors that prevent another 9/11, and those have nothing to do with TSA. Even if you could bring box cutters onto the plane you wouldn't be able to take it over. Plus, like you said, awareness among passengers. That also has nothing to do with TSA.
There are others in the this comment section saying it is easy to take a gun through TSA. If that is true, why would an attacker want to bring another box cutter? If the TSA is ineffective, couldn't someone bring a tool to break the cockpit door?
My point is that none of these things have to be impenetrable. There is a swiss-cheese model to safety. TSA doesn't have to be 100% effective to be effective. Every layer of security adds up. There is no single component responsible for all airline security, not even the cockpit doors.
If TSA is just theater, couldn't an attacker simply bring weapons sufficient enough to hold off the crowd and break the door? The hijackers on 93 only had box cutters.
It is the combined perception of airport security and the perception that passengers will fight that deter bad actors from even trying.