I wonder why fingerprint readers act up for some people, is there some sort of physiological reason? It works perfectly for me, but I've seen how much a tech-savvy friend of mine struggled with it (for them, faceid was a godsend).
The ones on their laptops, however, have been reliable. Possibly there was a generational improvement in the equipment before it hit the laptops, and my problems were just because I had an early model on my phone.
My home country is a very humid tropical country in Asia.
When I was in the United States (I was in a cold dry place), the fingerprint reader works perfectly. Instantly. Never had to try a 2nd time.
In my home country, it works like 40% of the time.
However, if I'm in an air conditioned room in my home country (the AC sucks out all the humidity), then the finger print reader starts working perfectly again.
So, humidity and moisture/sweat on my hands might have been a factor.