Most Americans prefer not to spend money they don't have. I know this is hard to believe, but debit cards are far more common than credit cards, and are used for 50% more transaction dollars than credit cards: http://www.nerdwallet.com/blog/credit-card-data/credit-card-...
Posting rather late here, but that data blows my mind. Are you certain they are counting "debit transactions" properly? Or are they counting all magstripe transactions done by a debit card as debit? I was specifically referring to transactions that require a PIN, which basically removes your ability to do chargebacks.
I honestly can't say I've ever seen someone type in a PIN code on a PoS terminal in recent memory. I also tend to pay attention to this stuff. That's of course not worth anything as a data point, but I'd have expected if they are used 50% more than credit transactions I would have at least noticed it once or twice.
Just to be clear here: A debit transaction is identical to an ATM transaction (from the UI point of view). Just swiping your combined ATM+debit card at a terminal and treating it like a normal Visa/MC transaction is not what I meant. I also (used to) prefer the debit card in that scenario for the reason you mentioned. Then I got financially responsible and realized I was simply taking on more risk than I needed to - automated payments on my Amex work just as well.
Edit: I just re-read the data, and it looks very much like they are treating bank cards with a Visa or MC logo as debit card transactions. If so, the data is extremely misleading as no PIN codes are involved, and your fraud protection is nearly identical to an actual credit card in that case. This would also jive with my personal experience as well.
