Originally Posted by
tmiw
While this is normally true, there are merchants who actually accept AmEx yet heavily discourage you from using one. NFC would be a workaround for such places--until they realize that's what's happening and have it disabled/stop people from using it, of course.
It's up to the merchant to hard-code card types in their system. Before Apple Pay adoption, two local places I frequent both said no Amex, but after their new POS terminal upgrades, Amex would go through at one while the other is actually hard-coded against it.