How long before someone is killed by this?
Imagine using facial recognition tech in a crowd, and getting a false positive on some highly dangerous wanted person like a terrorist suspect. That person is followed by CCTV cameras getting into a car, and driving to a house. Your house. The police bust in, guns blazing (OK this part is probably a lot more likely in the US than the UK) and you get shot dead in the confusion.
All because a poorly design system had mistaken you for someone else, and led police to your door.