Why do protesters have an expectation of privacy? You go out in public and someone might see you there. If you're a peaceful protester, it shouldn't matter. If you're performing criminal acts while protesting, you should be stopped.

I see a lot of people saying that it's terrible that protesters might be identified. I think at least some of these people are secretly upset that people can't break windows and burn cars with impunity.

> Why do protesters have an expectation of privacy?

You asked about harm. Expectation of privacy is a different matter. And they might expect privacy due to wearing masks - why is it okay to regulate those, but not facial recognition? While I'm against regulating facial recognition, I'm at least aware of the harm it causes.

> If you're a peaceful protester, it shouldn't matter.

It shouldn't, but it does. If the government and corporations were so perfect that it wouldn't matter, you wouldn't be protesting in the first place.

> I think at least some of these people are secretly upset that people can't break windows and burn cars with impunity.

This is a pure ad hominem, and not a very good one either. The motivations of an imagined 'some' people are irrelevant to the harms of surveillance and facial recognition.

Governments might decide they want to retaliate against peaceful protesters, if the peaceful protests are causing problems for their agenda. This would have a tremendous chilling effect on protest.

Governments have retaliated against protesters for centuries. They don't need face recognition to do it. Even now, motivated individuals regularly identify and shame individuals involved in various public demonstrations. I find this fixation on the anti-protest use case of facial recognition to be very bizarre. Is a ban on smart doorbell cameras really going to prevent a state actor doing what it wants?