It's not like that at all. There are tons of exceptions that can occur when charging a card. Yes, cards get lost but more often than that, cards will get canceled or closed for various reason. Also, there many people who actually max their credit limits out regularly and therefore a credit limit is hit and the card can no longer be charged any further. Card accounts can be temporarily locked down due to fraud or irregular account activity. Charges can be blocked due to certain characteristics of the charge or the merchant. And yes, of course people do lose cards and get ones, with new numbers, etc. Cards also regularly expire, too, and the expiration number will change even if the card number does not and they must match in order to charge the card.