In Germany, shopping carts typically have a deposit system, where you have to insert an Euro into the cart to use it, which you get back when you return it. So that is basically a build in fine for not returning it.
In Spain we used to have the same system. However it’s been a while since I’ve seen it, most carts still have the euro slot, but they are not chained, so you don’t need to insert a coin.
The past year or two I’ve found several stores where they are abandoning it. I presume because people carrying cash, especially coins, is becoming rarer and they don’t want to inconvenience their customers?
Strangely enough, carts still get returned even at these stores.
There’s a store chain, Costco or Aldi’s maybe? In America here that dies this but it’s only a quarter. Which is next to nothing. For reference, a load of laundry is between $1-2 in just a normal machine, plus dry time, (so 4-8 quarters). So just to wash and dry a single load of laundry for me, for example, is 12 quarters, $1.50 each of l for washing and drying.
So that cart deposit thing could use some improvement. Regardless I’ve never shopped at that store, but I do just return my cart like a civilized person.