This is how I felt a couple years ago when using Google Wallet. The people at the places I frequented got used to it. I essentially trained these places in preparation for Apple Pay. I guess we can call Google Wallet an Apple Pay Beta testing app?
If they don't known what to do, tell them to press Credit/Debit or just Credit. Not mobile payments or anything like that because last time someone did that, it came up with a CurrentC-esque QR code.