Self-checkout is annoying for this very reason:

I only do this kinda crap when I’m alone as I don’t like to drag anyone else into my clownery, but one time at a self-checkout some cheese wouldn’t scan and no one was available to help. I waited for five minutes and then gave up, paid for the other items.

Then I walked out the door while half-shouting, “I’m leaving! If anyone wants to stop me, now’s the time!” No one did and I got free cheese for wasting my motherfucking time. No one said or did shit. And I’d do it again. If anyone wants to lay a shoplifting charge on me for $5 of cheese, bring it. I have lots and lots of money for all the lawyers and I’m spiteful.