Returning the shopping cart is an easy, convenient task, & one which we all recognize as the correct thing to do. Simultaneously, it is not illegal to abandon your shopping cart. No one will punish you for not returning the shopping cart. You must return the shopping cart out of the goodness of your own heart. A person who is unable to do this is no better than an animal, an absolute savage who can only be made to do what is right by threatening them with a law & the force that stands behind it.