I am old enough to have lived in Germany when they were not coin operated, and most carts were returned at that time as well.
Though occasionally you saw a cart far far away from a supermarket, where someone had basically stolen it, either teenagers to have fun, or someone asocial who, I don't know, used to carry all the shopping home? I don't really know what they did with it.
And it was the cost of replacing those stolen carts that drove the adaption of the coin operation system. Not that people just left them in the parking lot. Some supermarkets also tried a system where the cart locked if you moved it out of range of some radio in the supermarket, but that one really didn't take off.
(Also, quite a few people in Germany just do shopping by walking or biking to the supermarket).
Though occasionally you saw a cart far far away from a supermarket, where someone had basically stolen it, either teenagers to have fun, or someone asocial who, I don't know, used to carry all the shopping home? I don't really know what they did with it.
And it was the cost of replacing those stolen carts that drove the adaption of the coin operation system. Not that people just left them in the parking lot. Some supermarkets also tried a system where the cart locked if you moved it out of range of some radio in the supermarket, but that one really didn't take off.
(Also, quite a few people in Germany just do shopping by walking or biking to the supermarket).