Exactly two things have made airplane travel safer since 9/11: reinforcing the cockpit door, and convincing passengers they need to fight back. Everything else has been a waste of money. Add screening of checked bags and airport workers and we’re done. Take all the rest of the money and spend it on investigation and intelligence.
The above two are exceptions to the rule. Every other “security measure” that travelers have experienced since 11 September 2001 have been little more than security theater.