IMO, the agency is staffed by far too many ex-cops and retired military/war heroes who foolishly believe that by serving as airport screeners that they are actually defending the nation and that you get what you want from people by yelling at them, as if they were outnumbered by bad guys in the hood rather than simply looking for guns and bombs in suitcases and on one's person.

In most other countries I've visited over the past 5.5 years, the screeners are quiet, polite and usually somewhat deferential toward the travelers.