> First off, you can't just pretend like 9/11 doesn't count in pre-TSA security stats. Four planes were hijacked within an hour of each other on 9/11 and zero have been hijacked in the last 17+ years?
Prior to 9/11, there were 14 years with no US hijackings (failed attempts are a different story) and 27 with no deaths on a commercial aircraft due to a hijacking. 17 years with neither hijackings nor hijacking related deaths is not a clear improvement that calls for credit anywhere. Since the 1980s, hijacking events have been so rare that it would take many decades under a give policy regime before and after a policy change before you couls have even remote statistical confidence that my quiet period
Really, since at least the 1980s, hijacking is so rare that it would take an extraordinarily long time to have even remote confidence that there was an increase in safety, much less of assigning a specific cause to it.
And, on assigning cause, if there was a reduction in hijackings post-9/11, well, there's a pretty good reason to think that al-Qaeda and the passengers of Flight 93 jointly might be responsible without any government policy as an intermediate cause.
Hijacking became something passengers would no longer be likely to accept as a “cooperate and noone gets hurt” event, which rendered it pointless as almost anyone has ever used it (even as al-Qaeda used it on 9/11, which while it doesn't factually fit that model clearly required for effect that people believed that it did.)