After a few train hijackings or whatever I'm sure we'll need mugshots to ride it too.
The most common reason for guns and threats of gun usage on flights in the last decade of us flights have been us air marshals getting in arguments, or simply leaving their guns lying around aircraft.
The TSA theater is BS that has nothing to do with making people safer, so the existence of an actual threat isn’t relevant.
In the post-9/11 world people aren’t going to just silently wait for rescue, and the core threat (the ability to enter the cockpit) has been stopped.
Hijacking a plane to go somewhere (at least in US airspace) isn’t going to work.
So any attack will be terrorism. Assuming something planned (as 9/11 was) you can “easily” kill a lot of people with a train - as numerous accidental derailments have demonstrated.