As someone who spent a good deal of their late teens and early 20's working as a stockman for Walmart, I have first-hand experience with this. While I had an assortment of duties, my primary duty was to make sure the cart corral was full. It was not to make sure the parking lot was clear of carts, I only had to collect carts from the parking lot in two instances; 1) when we were out of carts in the corrals and 2) at the end of the night to prepare the corrals for the morning.
That said, collecting carts from the parking lot was a regular thing. Now this was a while ago, but I can't imagine things have changed much, but most carts were not returned to the cart return areas scattered around the lot. They were left in empty spots or pushed up onto the median areas.
Most of the people who left them do it for one of a few reasons:
- They did not care. They loaded their shit into the car and just walked away from the cart. This was honestly not the most common though.
- They were a frantic mess getting their kids in the backseat, loading their stuff in the back of the car/SUV/ whatever, and then grabbed the cart, looked at the return stall, thought about it, and just decided they couldn't do it. More common than #1 but not as common as #3...
- They were just going with the flow. Once one cart is left somewhere, it becomes the new cart return area. Most people stack carts on top of each other where ever they happen to be, a return stall or some random spot.
So, in my experience, most people who do not return carts to the store or the return stalls aren't doing it because they're assholes, most of them are doing it because there's a more convenient option presented to them in an unofficial manner. Some do it because they're jerks, sure, and some do it because a cart is just one more spinning plate they don't want to deal with, or it's raining/snowing and they don't want to deal with it, or whatever. But most, in my experience, are just going with the flow of what others have done before them.