No human police offer could process these many faces or remember suspect databases, of course our current tech is going to be faster here.

More inaccurate, sure, but I'm thinking that with the amount of government money involved it'll slowly improve. Or at least society will reach a stage where we don't care about the incorrectly flagged anymore.

This isn't the right question. Cars help the police to move much more quickly than they could on foot, for example, and properly used can be part of a system that values justice and human rights.

A better question might be: "given how accurate this facial recognition system is, what if anything in addition to a match should be required for an officer to detain someone matched by it?".

I don't have an answer for this one. This tech is new, and complex, and hard. We'll likely abuse it before we figure out how to properly balance human rights and protecting the public.