It probably won’t be much if any cheaper than what they are currently doing but I do like what Bruce Schneier has to say about the security aspects of it.
In both Secrets and Lies and Beyond Fear, I discuss a key difference between attackers and defenders: the ability to concentrate resources. The defender must defend against all possible attacks, while the attacker can concentrate his forces on one particular avenue of attack. This precept is fundamental to a lot of security, and can be seen very clearly in counterterrorism. A country is in the position of the interior; it must defend itself against all possible terrorist attacks: airplane terrorism, chemical bombs, threats at the ports, threats through the mails, lone lunatics with automatic weapons, assassinations, etc, etc, etc. The terrorist just needs to find one weak spot in the defenses, and exploit that. This concentration versus diffusion of resources is one reason why the defender’s job is so much harder than the attackers.
He then goes on to explain that security screener can also be an attacker against a terrorist defender. By doing this the screener gains a big advantage and only has to find “one weak spot”. It’s great stuff and also has connections to this post I made.