Originally Posted by
Points Scrounger
I don't recall hearing even anecdotal reports of a transaction where one card was okay, but the other type was specifically not allowed (Visa or MasterCard only - NOT both).
I think for the most part, at least in the US, it's the acquirers and processors that have set it up that way, sort of a like a "bundled package" (similar to how cable company offer cable TV + internet for $X per month) deal for small to medium sized retailers and businesses.
i.e.: They offer a "VISA and MC" package, while AMEX and Discover are extra features.
Larger retailers like Sam's Club or Costco can leverage their own exclusive deals directly with MC or AMEX.