[throwanem]

One quibble: MasterCard and Visa are associations, not issuers. (AmEx is sort of both - iPhone to Visa's and MasterCard's Android.)

I don't know that processors have a lot to worry about here. It's been a few years since I was in the space, but from a dev perspective, there'd have to be some really compelling reasons to implement (and pay fees for!) an integration per card type, rather than one integration for all payment cards.