Speaking as one of those workers who did that job, leaving your cart propped up in one of those planter islands is the second best thing to do behind actually returning it. It's really not a big deal.

I'm not sure if I agree with the framing that it's a minimum wage worker doing it. I think of it as Costco doing it. The only time it really makes a difference to the worker is at the end of the day when it's time to get them all in to lock up.