[deanly]

VISA et al can still take away a merchant's ability to charge customers' credit cards if they catch you asking for minimum payments on cards or offering discounts for cash. It doesn't happen all the time, and usually consumers don't report establishments that practice this behavior.

[cma]

Minimum payments maybe. But you have the right by law to give a cash discount (and apparently the right to charge a credit card fee):

http://www.interest.com/credit-cards/news/you-soon-could-be-...

From that article it sounds like it was part of a lawsuit that was settled. I had thought it was through one of the consumer financial protection bills that happened after the housing bubble pop.

[deanly]

ah, yes, that particular angle could probably use some more research. I haven't read the consumer financial protection bills, but then again most legislators probably haven't either, and there certainly could be some loopholes that someone is trying to exploit right now.

Also important to note that most merchants opted NOT to switch to charging extra because it would have upset their customers, so really, by allowing that in the past, it primed consumers to expect the same price for both. Tricky devils...