some people HAVE secret information on there lol.. or very private information..
the real concern is about the encryption on the chip and whether thieves can actually retrieve and break the encryption and get your fingerprint off the SoC/chip, if there is a flaw in that and that it can be hacked... well that would be a disastrous epidemic
I understand some people want to lock a phone; I just don't see the need for it personally. And what would be so horrible about a thief having my fingerprint? I leave fingerprints everywhere and I think the gov't has mine on file with my birth certificate. What good would that do someone? It's not private, just unique.
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Using your logic, why would anyone with a substantial amount of money in their checking account have a PIN on their debit card? How could someone with a substantial amount of money possibly let their debit card fall into the wrong hands?!
Maybe you don't see the need for PINs and passcodes, but I'll keep securing my devices the best ways I can.
Because I care about who has access to my money but not about who has access to the phone number and photos of people that I call. (That's why Apple has an OPTIONAL lock--people who need a lock, use it. People like me, who don't care, don't. But EVERYONE has a pin # for their bank account!).