A law like that would be a violation of our rights
We have a right to not clean up after ourselves? Tell me more
The fact is you're borrowing a cart from it's owner, probably a store. If the store requires you to put it back and you don't the they would be within their rights to sue you over it. The only reason they don't is because their damages would be massively less valuable than their legal fees and the time it would take to present a lawsuit.