In fact due to an odd lacuna in the law inherited from English common law, if someone in the business of selling cars (say, a used car dealer) sells one to you,

In fact due to an odd lacuna in the law inherited from English common law, if someone in the business of selling cars (say, a used car dealer) sells one to you, that car cannot be repossessed (although the used car dealer is liable for the cash amount of the car). This is precisely to protect consumers, who can thus reasonably expect that if they buy an X from someone who deals in X, they are fine. This does not, of course, apply to buying Xs from people not in the business of selling Xs. If your garbageman offers you a deal on a car, that car can be repossessed.