Generally with a credit card, or many banking systems more generally, because they predate computers, it's possible that a charge might be accepted even if there's no knowledge whether the money is in the account. As long as the person who was supposed to have paid is identifiable, the money is taken from their account anyway in the end, and if they don't have it, they get sued and their wages garnished, and if they also don't have wages, that's a small enough percentage of people that it's part of the cost of doing business.