The trolley analogy doesn't really hold up in this context, does it?
The incentive to do the right thing that a coin-deposit shopping cart ("trolley") adds is the ultimate return of that coin. It's not much money, but it is nonetheless returned when the cart is put back where it belongs.
If a cart always costs 50 cents and there is no hope of ever getting that money back, then: The monetary incentive to return the cart doesn't exist.
The incentive to do the right thing that a coin-deposit shopping cart ("trolley") adds is the ultimate return of that coin. It's not much money, but it is nonetheless returned when the cart is put back where it belongs.
If a cart always costs 50 cents and there is no hope of ever getting that money back, then: The monetary incentive to return the cart doesn't exist.