Walt Mossberg on his frustration with anti-Apple Pay merchants (emphasis mine):
Of course, any retailer can accept or reject any form of payment it desires. CVS could announce tomorrow that it will only take cash. But Apple Pay is just a quicker, more secure, way of paying with your own credit cards — the very same ones that CVS accepts in plastic form. And CVS has already invested in the terminals that accept these familiar cards in digital form.
Even Apple, notorious for keeping a tight grip on its products, allows fierce competitors like Google, Amazon, Spotify and Microsoft to offer their apps on its phones and tablets. (Even the invitation-only test version of CurrentC is in Apple’s app store.) And CVS stocks multiple brands of most items, even those that compete with its house brands.
If you are behind on the Apple Pay-CurrentC story and want an overview, Walt's post is a good one to read.