Re: Surely though
People really seem to be missing what these numbers mean. Imagine the police were searching for me. This system would identify 50 people, one of which would be me.
You're making a big assumption there. Odds are the false negative rate of the system is no better than the false positive rate. Maybe you were wearing a hat, or glasses, or the camera didn't see you at the right angle, or you just weren't there that day. In which case of the 50 people identified, none of them would be you.