"The problem is that under the terms of their MCX contractual agreement, [the merchants] are not supposed to accept competing mobile payments products like Apple Pay, according to multiple retailers involved with MCX, who spoke on the condition of anonymity. If these retailers break their contracts, they will face steep fines for doing so, these people said."

http://www.nytimes.com/2014/10/29/technology/apple-pay-runs-...