Sorry to disagree, could be on the way in they will give you the going over. But once there if you dont fill the Profile or look weird, they might ask a few questions to clear the person of anything. Now if you are of Arab descent then Id agree with the 3 hours, even if a US citizen.

on the way in they are trying to prevent people who are trying to get work (usually not a problem with citizens of A Western Country) or can be a potential security problem/risk.