These kinds of people piss off the cashiers too.
Take it from me, I work at one of the busiest stores in one of the busiest malls in Minnesota. On a Saturday you can imagine the lines get insanely long, and there's always the dumbshit that's supposed to be next up in line, and they're talking to their stupid friends or playing with their smelly baby or staring off into space with a ridiculous look on their face, when they're supposed to be NEXT IN LINE.
And you wave to them and call out loudly "I CAN HELP WHO'S NEXT" and they STILL don't move their ass, even while everyone in line behind them is giving them a dirty look.
It's like, shit, do you even WANT to check out, you dumb customer?!