If that is the case, I would think the person could say something, like: excuse me, but I need more space to get by you. Would you mind moving a bit, please, so I don't hit you? running into someone is rude and if it is an accident, the person who hit you owes you an apology. (IMHO)Maybe their disability prevents them from controlling the cart they're driving very well. . . And they don't have anyone to help them.