Actually, that's not true. As of today, because of this[1] $7.2B settlement, merchants will now be able to charge customers that use cards a fee for doing so. This is already the case in Australia as I understand it, and card use has not decreased as a result. I personally use cash for most store/ restaurant purchases (I used to work in the Merchant Acquirer space), so I will finally be getting a better price in addition to reducing my behavior-tracking surface area.

[1]http://newsroom.mastercard.com/2012/07/13/mastercard-speaks-...