“mogging” is a relatively recent meme representing a situation where one person next to others has radically better looks in some way or another, supposedly creating a subconscious atmosphere of their superiority. Typical examples are photos of bodybuilders next to regular people.
Pretty sure the original post is written in the context of a typical large US supermarket with outdoors parking lot.
There people often buy more groceries then they can carry so they go with the cart to their cars to unload them. After doing that you’re supposed to push the cart back to one of cart sheds located in the parking lot, yet many people just leave it where they unloaded it and drive away.