If we presume that the TSA wants to maximize actual passenger safety given certain budgetary and passenger annoyance constraints, most of its policies and procedures make little sense. When we add in the goal of making the public perceive that it is increasing safety levels and the resulting "security theater" tactics, they start to appear more rational. Does the general public believe that terrorists can't acquire fake ids and print out boarding passes to match? I suspect the majority of Americans don't think they are more secure because of id checking. So, why does the TSA do it? Perhaps the airlines have requested it as a way of circumventing ticket sharing, exchanges, etc.? Have they enlisted the government as the enforcer of their price discrimination model? When things don't make sense, I always presume there are some facts/circumstances of which I am unaware.