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?
The thumbprint and facescan reader on my phone straight up says that it’s not necessarily good enough to distinguish me from family members (especially if we look similar, which we do) when you go to set it up, so I’ve pretty much never used either.