Re: I'm disappointed
> The idea of a biometric door lock is very sound
No, no it's not.
In your examples, you are storing the dog-walker et.al's biometric information.
Why should they give you access to their phone, their own house (if they too have one of these locks)?
How are you storing that information? What if you get hacked?
It's not a good idea. I suspect it will be repeated on here many many times : Biometric data is not authentication, it's identification.