When people won't fucking stack the carts in the cart returns, or worse, will leave them right next to a relatively empty cart return.
It takes THREE FUCKING SECONDS to put them in the cart return, and maybe ONE second to properly stack them. However, for each cart that isn't stacked properly, it only amplifies the problem until it takes a lot more than a few seconds for the people responsible for returning the carts back into the store to get them all in line.
Oh, and let's not forget that it also wastes the space in the cart return. Which means that it spills out into parking. Which means that parking spaces get blocked.
In short... take the small amount of time it takes to stack the carts. It saves someone else a lot more than a few seconds.
...Oh, and it also means that other shoppers will actually HAVE CARTS TO SHOP WITH.
Me? I fucking organize the carts when I can, and no one's even paying me. The reason I do it is so that the next good guy that comes along doesn't have a harder time stacking the carts. That and it does encourage people in general to stack carts when they're already stacked.