Ok, I will give you two examples, but you will need to use your brain to try to adapt the problems to other situations. Can you do that? Great!

Example 1: So, let's say you're on a festival where cameras and facial recognition systems are used "for safety purposes" and everybody is feeling really safe because of that. Now some crime happens, like sexual assault or whatever. Nobody really saw the culprit and there's no usable evidence on the victim or crime scene, but cameras filmed him when he flew from the scene.

The images are not the best. It was dark, he ran quite fast and he was also wearing a black hoodie. Facial recognition systems worked hard on every frame of the video material and are somewhat sure (90% probability) that you are the sexual offender. You also happen to have a black hoodie with you and you were not with your friends when the assault happened.

Obviously you will tell the police that you were on your way to the toilet and that's why you split from your friends for half an hour, just as the crime happened. But what reasons do they have to believe you? The software solution is quite sure of two things: You are the suspect (90% probability) and the system found nobody else that matched the video frames. So, it can only be you, right?

Well, seems like you could go to jail for some time before the real culprit is found. Or maybe you will be convicted for something that you have not done. That is a real possibility when law enforcement starts replacing "real" police work with automated solutions which are prone to errors.

Will those systems even say that they are only 90% sure? Or will there be pressure on the manufacturers of those systems to only deal in absolutes and have great hit rates?

Example 2: You're on this march against right-wing politicians. Police is using cameras to watch the march and is also using facial recognition technology to save who attended the march, in case something happens. Your face is detected and linked with your personal information because a reference picture of you is already present in the passport database, which the police obviously has access to. Police says that the data will be deleted after the march, but somehow it's saved for testing purposes in a MongoDB hosted on AWS and never got deleted after all.

Elections come and go and now those right-wing politicians your protested against are in control. Or some hackers stumble over the database, copy it and sell it to whomever is willing to pay for that. Or some corrupt members of the police get payed a nice bribe for a copy of that list and they don't really care about "that data". Nothing of that really sounds unlikely in this day and age.

In any case you are now on a list of "political enemies" because you were on that march. Nobody knows what will happen with you from here on. Maybe you will just lose your job when working in a public institution, because there is somebody more "loyal". Or you simply don't get promoted anymore, although you are doing really great work. But maybe you end up on some kind of bounty list for some ultraradical people, who knows.

Just look over to Hong Kong. Would you really feel well when the Chinese government knew that you were attending the protests against the government?

From here on you might think about more examples where facial recognition could go really wrong for you, although you did nothing wrong.