I do get irritated by those who don't return shopping carts, but, another parking log etiquette thing that bugs me is people who don't park in one spot. The ones who park over the line. I get it, sometimes you get into a spot and you realize that you weren't quite in, but, there's this thing called "Reverse". So, put your car in reverse, back up a little, and adjust your parking so that you are securely into your one spot. The lot may be sparse now, but, as the day goes on, and the parking lot fills up, all spots may very well be needed and you are taking up a spot someone else could pull into. IMO, people who don't take the time to pull into one spot are just as rude as the ones who can't be bothered to return their carts.