This might seem like an odd complaint coming from someone in the I.T. field, but the self checkout lanes really annoy me. They're always screwed up.
For example, a couple of weeks ago I go into the grocery store and buy a single kitchen implement. Since it's only one item, I go through the self check out.
Navigating the screens and scanning it is not the problem. (After all, I set up and troubleshoot industrial barcode readers fairly regularly.)
The problem comes when I pay for the item with one of those brand new, multi-color 20$ bills. (The only bill I had at the time) I get change as if I had only put 10$ in the machine and the receipt comes out mangled because the last person yanked it loose instead of tearing it against the tiny teeth.
Does the snotty sales assistent believe me? Of course not. The pattern recognition software could not possibly be having trouble with the new bills. I'm obviously a technically challenged 'tard who can't use a self-checkout