I like the idea that there’s some shift that’s just getting carts all day.
“Sorry, Johnson, people haven’t left enough carts out lately. We’re letting you go.”
As far as I’m aware, that is the case for some of the crews at different stores. Mainly the ones based in larger malls or shopping centres that have their carts spread out over a large area. Those are the ones you would see using the ride-on vehicle with the trolley trailer hitched.
For the most part though, at least here in Aus, the trolley collectors are also responsible for cleaning the stores.