to your point: chasing terrorism is like trying to solve for all these (and many more) nefarious ways in which society isn't looking for wrongdoing. It's basically impossible to safeguard against every type of threat. Manage to lock down one sufficiently so that it's no longer attractive to accomplish ${evil_stuff}? Move on to the next one. We now see people getting run down with large trucks, since air travel is much more restricted. Everyone still suffers from restricted air travel, but will the TSA start inspecting every car driving over a bridge or an on-ramp now to prevent these new attack vectors? I sure hope not.