I'd argue the %s are not intuitive either way. In fact, if P(A) does happen, and there really is an unlucky doppelganger, that person is very likely to be charged. That could have been avoided with technology produced gave 5 other suspects that don't live on that block. Should it therefor be allowed for criminal defense if not prosecution?

The issue with the P(A) and P(B) argument is that police already use databases heavily, and most people don't have any problem with it. But why when it comes to facial recognition, is it too dangerous to use technology to drive efficiency.

If they're looking for somebody named Jane Doe, anybody with that name shows up on a list and police investigate. Of course if there are Jane Does in a 2 mile radius, they start with those. So why not just say if the system delivers a match within x accuracy and the person is within y residents (plus a variety of other variables), and x/y is below a threshold, then the match can be presented to police for further investigation.

Searching databases for matches is fine for names, or fingerprints, shoe prints, tire track, fiber analysis - but not faces? I personally wonder if it's really any different, or if its just better tailored for the media outrage machine because "China does it", or because "facial recognition targets minorities".