There are thousands of cameras at all major airports. They cover almost every square metre inside the terminal and outside on the aprons. You'd think that if Big Brother was so concerned about identifying and tracking people wearing headgear, there would be a general ban throughout the airport - which of course there isn't. Enforcement of hats at the gate seems pretty inconsistent - I didn't observe any instances yesterday at multiple gates serving both AC and WS (sample size: a half dozen gates at one largish airport); and plenty of people with chapeaus walked cheerily past the agents.