I'm confused. Are you saying that this is a unique problem to the US and that France used to have a different unique problem, that is, in my estimation, worse? And that it was solved by requiring deposits on the carts.
And instituting the deposits worked and you seem to be suggesting that the current existence of deposits is somehow vestigial and unrelated to the continuing discouragement of stealing carts?
There is a difference between leaving the cart in a random parking lot and not returning it and to decide to just take it (stealing). The latter is a deliberate action, that involves more work, not less.
The vast, vast majority of people here will bring their cart back, deposit or not. There are some b ok eck sheep but you will see maybe 2 carts left in a whole large parking lot (if at all). This is not a matter of deposit anymore, you can get coins at the reception desk.
So the problem of leaving the cats was not one we needed to solve.
People taking the carts - yes. It was just a small fraction, but enough for the shops to take action. They betted on there fact that 1 or 2 francs (this was before the euro) wrote be enough to deter people from yelling the carts with them. And it worked. And it pissed of the best majority that was not doing it. Today everyone is used to the system so it stayed.
I think (but this is just a personal opinion) that having the carts locked helps with their bulk transport
And instituting the deposits worked and you seem to be suggesting that the current existence of deposits is somehow vestigial and unrelated to the continuing discouragement of stealing carts?