A thief flags you down, grabs your phone and makes you unlock it using your thumb.
A cop opens the cop car door, grabs your hand and unlocks your phone, or even easier, face unlock.
Granted, guns and torture are rather effective as well, but is anyone entirely against fingerprint unlocking?
It may vary between models. Mine if you spam the wrong finger it just counts down 30 seconds before you can try again. But restarting does force a pass entry before fingerprint will work again. I guess the caveat is you have to be able to hold down the power and then select a restart.