Theres a coin activated mechanical lock on each cart, carts are stacked and chained together by these locks. To get one, you insert a coin (or a plastic token

Theres a coin activated mechanical lock on each cart, carts are stacked and chained together by these locks. To get one, you insert a coin (or a plastic token - these are usually given away as freebies by many companies if not the stores themselves) and that unlocks the chain. It's not about the money, no one earns anything from this. It's about putting something that you own (can be worthless, the emotion counts) in the cart which you can only possibly get back if you return the cart to any number of bays on the parking lot or next to the entrance.