My Dad told me how he went to the grocery the other day...and wherever he goes he parks super far away so no one can scratch his truck (LOL). Anyway, as he was pushing the grocery cart to his truck it was being stubborn like a rock was stuck on a wheel or something. He was fighting with it, and fell on his knee A few people stopped to make sure he was ok, and then mentioned to him that the carts can only go so far, like a lock system so people cant steal them. I never knew this, and apparently neither did my Dad. My Dad is ok though!