One thing I do like about the major credit card companies is the fact their security setup works by individual transactions instead of users. When you purchase an item on a credit card (or debit card issued by one of the companies) the company checks the transaction to see if it seems valid.
The other day I received a call from my credit card company informing me that they saw some apparent fraudulent activity. Needless to say it was fraud and the card has been canceled and a new one is in the mail. Credit card companies are doing it right in this regard by making it so each transaction is looked at as well as assuming trust with the customer when they call and claim something on their bill was not purchased by them.