Have you ever heard of the Shopping Cart Theory? It's gone viral on the Internet.
I return because of selfish reasons. I feel that if I don't return the cart then the store must employ someone to do it, enabling that store to keep their prices lower. I think Adam Smith would be pleased.
In all of these alleged measurements, no one accounts for the saint who brings their own : cart , sanitizer, mask and bags ( during non-holiday morning weekdays).
They enter and leave seamlessly without any unclean residue behind them.