Originally Posted by
msp3
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.
The merchant has to have an agreement with AMEX in order to accept the cards which is more than a merchant hard coding card types.