I don't know if/how you've never seen wind catch a shopping cart, but it can hurtle those fucking things. Mercifully the hurtling tends to be worst with the plastic ones because there's more surface area, but I've seen one of those smack a car head-on at like 25 kph on flat terrain on a breezy day.

You can go look up videos of even pretty modest winds gently pushing metal shopping carts around; they look like they're possessed.

Even on flat lots on windless days, you're not sticking it to the man; you're just being a jackass making someone's already insufferable retail job even less sufferable over 10 seconds of returning a cart.

"The store just puts those trash cans there to save money on cleanup and liability." Yeah, no shit.