[thom]

With Face ID you have to take your phone out, double click, then hold it up to your face and wait for it to work, then hold it out to do a contactless payment. With Touch ID you just take your phone out of your pocket with your thumb on the home button and pay instantly (you don’t have to initiate anything).

[thom]

Even if you’re just paying on the phone, the double side click plus wait is a wacky gesture to make compared to just moving your thumb down a bit.