The problem is that it says random people, but people aren't random. We don't periodically just stir all the people in the entire world and redistribute them across the globe.

In courts you'd get a situation where a jury is told there's only 1-in-10-million chance this evidence would match a random person. Only a few hundred people in the whole world could have been the one, and yet this suspect matches. And what they may not get told unless a defence lawyer brings it up is oh, by the way, six of those few hundred people were in the place where it happened and four more lived in the same street as the suspect.

Bob's Face ID may only match 1 in a million people. But if one of those "1 in a million" people is Bob's twin brother Dave who is always pranking him, and another is Bob's cousin Barry who doesn't look that similar to a person, but mathematically it turns out Bob and Barry's faces look identical to a computer vision system due to their bone structure, then Bob won't find "Face ID" much use.