Fingerprints are usernames, not passwords. Here is an excellent (and timeless) post on this fact: https://blog.dustinkirkland.com/2013/10/fingerprints-are-use...
I always thought that since the beginning, but unfortunately the world went into another direction. People always said "something you have and something you know", but now for most cases it's just "something you have - your body". Obviously if in the future remote mind-readers are invented, the "something you know" part will also get obsolete, but for now we should stick to it.
In Europe there is a regulation (PSD2) that defines a strong authentication as 2 of the 3 listed above.