Step 1 : take the phone off your pocket Step 2 : put it against the terminal while touching (not pressing) the home button. Step 3 : there is no step 3, you already paid because even if the phone wasn’t unlocked the NFC reader automatically unlocked it, opened your default card and validated the payment thanks to your finger being on the reader.
Compared to FaceID, no need to double press a button and to watch your screen waiting for the little animation to finish.
Don’t get me wrong, paying with FaceID totally works and it’s fast. But paying with TouchID wasn’t fast, it was instant and thoughtless.
All you typically need to do is lift your head up so FaceID can get a clear look... but when I'm sleepy, it's annoying.
Ideally, the phone would just have both... somehow... but this seems technically infeasible so I get it