I’ve been thinking about this a lot, fingerprints as passwords.
The rise of the Apple Touch ID which uses your fingerprint to unlock your phone and now process transactions with Apple Pay. Which in the system of the phone and the user, verifies the owner is present but isn’t a password. But you would think it is.
The iPhone doesn’t store your actual fingerprint -> but you have to reasonably expect, that if you digitally store your fingerprint (and chances are if you’ve been through customs it is already sitting in multiple databases around the world) it’s going to be compromised at some point.
This post by Dustin Kirkland from 2013 digs into it a bit more, saying that yes fingerprints are great as an identifier but not as a password.
Makes a heck of a lot of sense.