Re: How is the different from a wanted poster?
I think the real concern is how well trained the officials are in the likely unreliability of the facial recognition. If a human witness calls in and says they think the saw a person who matches a wanted poster, pretty much every law enforcement official knows to treat it with suspicion. They are taught in basic training that eye witnesses are unreliable so they will go in knowing they probably need further evidence.
But few will have had training on machine facial recognition. They will only have the information produced by the marketing people and what they see on TV, where, of course, it's almost instant and always 100% accurate. This could well lead to going in far more heavy handed because the suspect has "definitely" been identified. And that's before we even start looking at the large numbers of false positives where innocent citizens are stopped and questioned out of all proportion to the numbers of suspects identified.
Here in the UK (and I assume elsewhere) the Police employ a few "super recognisers", people who seem to have an uncanny ability to recognise a face months or years after seeing a photo of them just once. They'd love more people like that on the books. But I wonder what the results would be if they placed one of these people next to one of the Met Police Facial Recog Trial CCTV vans an compared the results, having both got the same "watch list" to check against?