One thing to remember is that in large part this is already done on social media and cell phones, or at least the facial recognition part is. They just make you label that person, rather than looking it up in a database somewhere.
Another thing to consider is that based on the way the machine learning works for this kind of thing, each AI doing the recognizing does it differently and likely stores that pattern differently. So when Google identifies someone, that pattern can’t be used by Facebook’s recognition engines, because they’re two different systems. There’s not AFAIK, a standardized facial recognition template for this sort of thing.
I would imagine that the best way to do it overall would be some kind of opt-in system, where you’d grant consent to the facial matching company to store and process your social media images, contact info, etc… along with a sort of “friends, friends & family, public, etc…” type level of consent for who could see that.
I’d even go so far as to suggest that it allow for public/private identities, so that if your “day” job is as Mistress Dominatrixa the Terrible, you could set up a public identity/face-matching profille that would identify you as that to the public, but identify you as Betty Smith of Sheboygan, WI to friends/family/financial institutions/etc… And on both, you could limit what you choose to expose- maybe just your name, maybe your name & email, etc…
That way, I imagine if you were to wander around with some sort of smart monocle or something, it would identify some people but not all, and of those it identifies, you’d only see what they wanted you to see, which might be commercial- you might be in the grocery store, and your digital monocle might recognize a guy, and it would say “Joe Smith - Joe’s Roofing (222) 333-4444 for all your roofing needs!” without really letting you know anything about Joe. Or people might be stupid and list everything on there for anyone to see; their choice.