I wonder why.
(In my case fingerprint scanner was forgetting my fingers in a week or my fingers changed in a week when summer ended - the only clue I got is that during winter skin gets dryer and might influence scanner readings, it was very frustrating)
I was hoping that Apples push for that would force other manufacturers to adapt it also.
It doesn't forget my fingers, but it won't let me in if my hands are very damp (like after a shower). Though I do get some sour grapes out of the fact that it's not a bad idea to force me to enter my PIN once in a while, so I don't forget.
For most users, the fingerprint sensor on Pixels works reliably - and when it does, it's also very convenient, because your finger pretty much lands in the exact right spot when pulling it out of the pocket.