Maybe because it's a bank. Unfortunately, banks are not notable for their customer service these days.

Or maybe it's that the credit card companies can't require you to appear in person to dispute the charge, because there are no branch offices and they don't have the staff to deal with it.

I read an article recently pointing out the dangers of assuming a debit card has the same protections and so forth as a credit card - NOT SO! We happily sign up for these little things, without reading the fine print. There is no fiduciary insurance, for instance - and if you buy something with a credit card, it's got a certain amount of insurance built in. Not the debit. The article was in my Fidelity quarterly magazine, and pointed at young people learning about finances. It's basic point was - don't use 'em if you can help it.