This is such a strange phenomenon to me. In all the countries I've lived in, all but a few select stores have a dongle on each cart that takes a coin to unlock it from the chain of other carts. It's perhaps the cost of a back of toilet paper, but that seems to be sufficient for it to be exceedingly rare to see an abandoned cart. One can only imagine that any such carts are quick prey for enterprising teens looking for a quick boost to their candy fund.