I’ve never been able to get he fingerprint reader on my iPhone 6 to work more than about 1/4 of the time. I’ve registered my finger(s) dozens of times. It just doesn’t work. My fingers must be defective or something.
Anyway, I’m not sure biometric systems are really all that great an idea. The digital representation of a biometric feature can be stolen, but unlike a password, I can’t respond by changing or revoking that part of me. It’s just forever broken. For applications where security really doesn’t matter, like unlocking a phone, I guess they’re OK. I’m just uneasy about the push to use them for serious things.