The only place so far where I can safely use Apple Pay without causing any frustration from cashiers is Whole Foods, cashiers in the rest of the stores either have no idea if the Apple Pay is supported or the terminal itself is not "enabled" to support Apple Pay.
Some of the retailers in the States are protesting Apple Pay and disabling it on the terminals even though it would otherwise be fully supported. Home Depot did this awhile back, they were one of the first places where Apple Pay worked and then it stopped working due to some corporate hissy fit.
That's a political decision. Stores like you to use store cards wherever possible (where they get a profile of what you've bought). Banks have to share profits with Apple for Apple Pay which is why they try to avoid it.
