Theory 1: I’m not touching the reader in the right place. Maybe the sensor is on this side or that. Try hovering the phone all over the POS box.
Theory 2: Maybe my phone is not working. Try waving it around again while cashier has this “get your shit together” look on his face. Pull out CC.
Theory 3: The reader supports NFC but not ApplePay, so now I’ve wasted my time. Pull out CC.
Theory 4: Its not even a NFC reader (because there seems to be no standard way of telling by just looking at them). So, now I’ve wasted my time. Pull out CC.