Bullshit security is very easy to do by accident. Step 1: OMG there's this new threat. Step 2: OK, it doesn't look that risky. Still, you never know. Step 3:

Bullshit security is very easy to do by accident. Step 1: OMG there's this new threat. Step 2: OK, it doesn't look that risky. Still, you never know. Step 3: I know, that new security check/ban/whatever has non-trivial costs. But we can't do nothing, can we? --- It's a matter of assigning blame. If whoever calls the shots change nothing, and something happens, his head will fall for ignoring that new threat (even if he didn't and made an actual cost/benefit analysis). Similarly, taking someone off a watch list is very hard. Also see how we are sliding towards a total surveillance state, ostensibly to stop terrorism and child abuse, but actually to stop particular forms of copyright infringement.