One of our interns this summer used to work in one of the London airports, where his job was basically to tell people that they were allowed strictly one bag, and yes, that little plastic bag they're carrying with a book they just bought counts as one bag, and yes, you're going to stuff your purse into your backpack because that counts as a bag too, and so on.
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.