Aside from the standard "customer service" jadedness, there's a class stratification at play: people who have to take a TSA screener job to pay the bills, versus people with enough income to fly. When you put an underclass in control of the overclass, don't be surprised when they try to wield whatever power they can, regardless of how disproportionate.
It would be an interesting experiment to staff a TSA gate with frequent fliers selected "jury pool" style (say, one day of service for every 100k miles flown annually), and see if both passenger and agent job ratings are any different.
I would be great at a job I knew I only had to perform for one day (or even one week). I also wouldn't be terribly concerned with upholding rules and laws, and just do it how I would want it to be done. Plus it would be fun and different, almost like a game.
It would be an interesting experiment to staff a TSA gate with frequent fliers selected "jury pool" style (say, one day of service for every 100k miles flown annually), and see if both passenger and agent job ratings are any different.