Theory: personal choice and responsibility is reduced as we are all told to queue in line (multiple times), are directed through the airport and onto the plane, and generally are corralled into all doing roughly the same thing. We're told when to buckle our belts, to sit down and not stand up, and generally treated in a way (other than when flying) you'd only treat a child. With that removal of personal choice and responsibility seems to come a removal of accountability and the occasional acting like an idiot. I suspect the fact many people are out-of-time-zone, tired, drunk or hungover often doesn't help either.