I thought I got behind them all. I had one years back telling the cashier he had kids out in the car, just take care of it so he could get out there to them. The more the cashier argued, the louder he got. Well finally they finished. I was walking behind him in the parking lot, watched him get in his Caddy, no kids, no one else, and pull off. Nice guy.
I've commented to cashiers about this, and have been told the management tells them to let it slide so as not to upset the customer. Which is worse, one upset jerk, or an entire line of upset shoppers. I've then gone over the the "manager" and told them if that is how they want to treat customers, that I am also one, and will no longer wait in line behind these folks, unload all my stuff where ever I find him, tell him I no longer need these items, and he can keep them.
They don't care.