> your privacy ends where my safety is concerned

and I dispute both the premise and that this is a legitimate instance of it.

Modern liberal democracies have until pretty recently come down strongly on the side of privacy. For the most part, in such societies, detaining people and making them answer questions or identify themselves has required significant objective evidence to suspect them of wrongdoing. Searches require stronger evidence, and often judicial oversight. Surveillance dragnets have traditionally been forbidden or strictly limited. In short, people have only been expected to give up privacy in the name of safety under narrow circumstances.

What the police are doing with facial recognition in the UK is anything but narrow. Nobody has made a good case for circumstances in the UK being so dire as to demand people be unable to walk down public streets in near-anonymity.