You have to look at it from the TSA's point of view.

Terrorism is something they can't control, and they know it. There are just too many ways to do something, too many uncontrollable circumstances. But you can't just throw up your arms and do nothing - you have to do something to prove you are doing your job.

So you attack what you CAN have an effect on. But even then you can't balance out some peoples paranoia versus other people's laizze-fair approach. Not to mention you don't have the resources to do it, or the brainpower to figure it all out in any case. And to get the money, well you have to make it look like you are totally in control.

So you implement random policies. None of them are really going to stop anything, and you know that. But they are random, so they are not in your face enough to get travelers really riled up. And it makes it look like you are doing something really serious, even though it really is just a bunch of smoke.

It all comes down to the government. No, actually, it comes down to the people. The ones who want to hype security. Use it as a rock to throw in their political squabbles. Keep from actually doing anything productive by hyping up the unproductive.

What worries me is that this so distracts from real security measures, which is better security staffing, better monitoring, and eliminating the threats in the first place, instead of how to stop the bombs after they get in the airport.