BombOmOm

The gold standard is providing something you know (a password) alongside something you have (an OTP or fingerprint). This is two-factor auth in a nutshell.

using your face, fingerprint, or PIN

You leave fingerprints and images of your face everywhere you go; and in the case of someone spoofing those, there is zero way to change either. Such public information is not the foundations of a secure system.

And a PIN is just a shorter, shittier password. Why the hell would we replace a normal password with the least secure, most shitty version of a password?

You want to help people so they don’t feel murder is their best choice in life, and if they do, you need to stop the threat. Having a camera go ‘someone might have a gun, I promise this isn’t the 1000’th false positive’ right as they start murdering people isn’t helpful.