There is always police at our Target and Walmart. I know it's not BF usually if there is not a fight.
I go w/ my DH and sister. DH is the driver/cart watcher. Usually it's his job to get a cart, park it in an uncongested area (maybe the diaper aisle or furniture) and then watch it while we work our way around the store and bring things back to the cart. It usually works for us.