I think part of the problem is that a significant portion of the US doesn't fly often enough to be greatly inconvenienced by this. And, of course, the media can always find people willing to say "Well, if it will make us safer..."

Imagine the outcry in New York if they announced that they were going to install metal detectors and x-ray machines at the entrance to every subway stop. --That would (hopefully) never be implemented because the number of people who would complain and campaign against such measures would be much higher.