Actually there is an expectation of privacy.
The argument that "if you're in public and are filmed" it's not an invasion of your privacy specifically relates to things that are considered "legitimate public insterest",. If you're tangentially caught on a news-report about a house fire, or an event, or something like that, for example. Of if you're in the background on a cop's dash cam during a traffic stop, etc...
Beyond that, no one can use your image without your consent. There's a reason that members of the press need credentials and will usually walk around in a jacket that says PRESS on it; so that people know that they are in a place where they are likely to be recorded and can move away from it.
There's a reason that, if a movie is shooting a scene and they catch a few background people, they have to send a poor production assistant running around with release forms so that those people can give their permission...other wise the film can't use the footage.
Some incel recording a woman for his own personal spank-bank doesn't fall into either of those categories. And anyone who is trying to claim that they're all the same thing is a fucking creep.