Do you return the cart?
Are you too busy?
Do you think its someone else's job?
Why leave It on the grass or curb?
Why not just turn It over on its side and leave It in the middle of the parking spot?
How good would It feel to return It to where It belongs?
ie- the cart corral or at the front of the store

Just some thoughts to ponder.
Have a most triumphant day.