Yes, true. I agree that that is the most effective part of modern airplane security. I doubt all the crazy TSA stuff has any real impact. But resistance by the passengers seems to be working so far in preventing another 9/11. So, hopefully, the same will extend to spacecraft. Of course, nothing is preventing someone, now or in the future, from buying their own airplane/spaceship and crashing it into something. So it is true that this still doesn't absolutely assure safety.