A couple of weeks ago I was listening to a baseball game on the radio. The announcer was talking about the new antiterrorism security countermeasures at the ballpark. One of them, he said, was that people are not allowed to bring bottles and cans into the park with them.This is, of course, ridiculous. The prohibition against bringing outside drinks into the park has nothing to do with terrorism. The park wants people to buy drinks from their concession stands, at inflated prices, and to not be able to undercut those prices by bringing in drinks from outside.
This is an example of a non-security agenda co-opting a security countermeasure, and it happens a lot. Airlines were in favor of the photo ID requirement not because of some vague threat of terrorism, but because it killed the practice of reselling nonrefundable tickets. Hotels make a copy of your driver's license not because of security, but because they want your information for their marketing database.
Security decisions are always about more than security. When trying to evaluate a particular decision, always pay attention to the non-security agendas of the people involved.
This is the root of the problem with virtually any post 9/11 security measure. It's not about security, and it won't stop a terrorist. Any terrorist. It's about profit and data mining.