Phones could allow much higher security if they supported 2 factor authentication. This could be face/fingerprint along with a typed or swiped password. This seems like a simple solution that leverages software that is already implemented. Just make it an added option in addition to the existing one
ETA: Sorry for the duplicate posts, I was getting error messages. Pls use this one.
I am surprised there is confusion about what 2fa is. Here is a simple definition: https://www.microsoft.com/en-us/security/business/security-101/what-is-two-factor-authentication-2fa
OP is correct 2FA refers to authentication via 2 factors, e.g. digital and pin. Phones use only one, you can unblock them with either a digital or a password, that’s LESS secure than 1FA and much less secure than 2FA.
The phone itself is not a factor, because every scenario starts with the attacker having access to the phone. If phones had 2FA someone would need to get your digital AND your password to access it, so a lot less likely to happen than having either of them.
The answer as to why that’s not an option is this would be impractical and people wouldn’t use it. But it would be definitely more secure than current system.