Actually there are significant legal differences between credit cards and debit cards. According to the US Dept of Justice's Office of Victim crime fact sheet.
credit cards fall under the Fair Credit Billing Act which provides
* If reported within 60 days, maximum liability for the unauthorized use of the credit card is $50
* If reported before fraudulent use, cannot be held responsible for any unauthorized charges
Contrast that to a debit card which falls under Electronic Funds Transfer Act

*
Limited time to report loss or unauthorized use of card
*
If debit card is reported missing before it is used, cannot be held responsible for any unauthorized charges or withdrawals
*
If reported within 2 business days, cannot be held responsible for more than $50
*
If reported after two business days but before 60 days, the most you could lose is $500

For most of us, the $450 difference is a big deal. Plus with a debit card, In case of fraudulent charges/losses, consumer often has to fight with bank to have funds replaced while you don't have to pay a disputed credit card account.