Parking lots are large and their aren't enough cart collection areas. These stores don't want to hire staff to collect them so they instead set up the lots without collection areas other than directly in front of the building.
"They pay people to do this" is not just and excuse and an attempt at Shifting Responsibility. Stores previously paid cart collectors. For some high school kids, it was part of one of a few jobs they could get. Not long ago, staff, or usually kids looking to earn spending money, would take your groceries to your car. I suspect the lawyers and the accountants nixed that.
I know one particular supermarket where there are no cart collection areas in the parking lot and the one in front of the supermarket is uphill on a significant slope. You could see where customers started pushing their cart back uphill but then gave up. Old people in particular had difficulty with that one.
The cart collection area is full because customers didn't have the strength to push their carts to fold them into the others. Or, annoyingly, the supermarket uses two or three different cart styles that don't fold into each other. Why roll your cart to an overfilled collection area that has carts lined up out the back and blocking the flow of cars in the lot?
The cart collection area is already in use:

I’m not only super thoughtful about carts but also inventive:
If I don’t see an official cart return area near me, I invent one - perhaps repurposing an empty parking spot that no one is using - or one of those patches of grass or mulch above the curb between parking lot sections. I figure I’m providing a service for others.. now, thanks to me, there’s a cart return spot that was not there before!
Okay, I’m being facetious - partly. There is a part of me that believes we often go too far with obeying rules created by sone dubious authority.
Yes, be thoughtful and considerate - often that is consistent with obeying “the rules” - but not always.
During the fake pandemic I was shocked by how slavishly obedient nearly everyone was to stupid masking and distancing rules set by stupid authorities. Then came the stupid testing and stupid shots. It was great a teaching moment regarding the difference between true thoughtfulness and blind obedience.