Very irritating stuff, particularly since it has absolutely zero bearing on security (why would the number of bags make a difference??), and so seems like a completely arbitrary imposition of force. I once chatted with someone who worked for the airlines and they said they didn't care about how many bags you carried (within reason), but the regulation is imposed by BAA (British Airports Authority).
So, our intern worked there for a month or two. Every time he let someone through with more than one bag he was told off by his supervisor after someone at the security checkpoint reported him, and eventually at one point when the guy was complaining about him once again, he had enough and he quit.
Why'd he do it? For the money. Easy money, not a tough job, not that risky. Yes, people think you're an asshole, but when you're a starving student with no money, you can cope with that.
I don't think being angry at these people would help any more than it would help to be angry at the piece of paper that a parking fine is printed on.
If someone is ready to be an asshole for money don't expect me to go easy on them because "they're just doing their job". You are responsible for what you do and "just doing my job" is not a legitimate excuse. If you're just trying to take the easy way out then I want to make your life a miserable living hell so you never think of taking this shortcut ever again.
I can't express how much I loath this non-excuse. People like Hitler are able to commit such atrocities because of literal armies of people "just doing their job".
The rank and file TSA agent who yells "take your shoes off" when you are in the line, looks at the metal detector when you walk through and checks your bags when they see something unusual...
... that's practically a minimum wage job on par with being a shift supervisor at Starbucks. And at most airports they're all contract staff - yes, even TSA is outsourced.
The people who are groping you for not taking the back-scatter scan work for a boss who owns the a company that contracts them to the TSA - they're so removed from any policy decision it's not worth venting unless you can see a senior person as they are usually staff.
In fact, you can see the pecking-order at airpots - the front-line contractor doing minimum wage tend to be black, latino etc and the senior staff are old white guys. The two-tier system has removed a great deal of diversity. Sad.