I don’t disagree, but considering how averse the police are to being filmed, I’m willing to bet they just don’t want to be filmed, despite their ignorance on the law.

In fact, I think a cop saying things like “It’s illegal to film cops” or “It’s illegal to film an ongoing arrest” or “It’s illegal to film a crime scene” cannot be viewed through the lens of ignorance. If you know little about the law you might misinterpret the law, or not know specific laws exist, or not know legal processes. But they aren’t “not knowing” the law, they are inventing a new law that doesn’t exist. They are inventing a new law that benefits them, and then using their authority, perceived knowledge of the law, and threat of force and violence to get their way.

If anything, cops hate accountability. And cameras are good at holding them accountable. And even if what they are doing is legal (such as clearing an unhoused camp), the public outcry will not be super pleasant for them. I remember the anger cops had when my state made them wear body cams, and I remember early scandals about cops disabling the cameras before doing horrible shit.