LAST December, Ed Bridges was mingling with the crowds of Christmas shoppers on the streets of Cardiff, UK, when the police snapped a picture of him. He has been trying to get them to delete it ever since.

Bridges hasn’t been convicted of a crime, nor is he suspected of committing one. He is simply one of a vast number of people who have been quietly added to face-recognition databases without their consent, and most often, without their knowledge.

For years, critics have warned that the …