>Someone will always say "there is no reasonable expectation of privacy in public", for whatever reason.
It isn't "for whatever reason", it is part of the first amendment. Just because you don't like it doesn't mean it hasn't been the law for a very long time.
Everyone has heard the phrase. It doesn't necessarily mean what the person saying it thinks it means.
For example, you can't legally photograph people in certain ways in public in some US jurisdictions. (Because "no expectation of privacy" perverts
There are also restrictions on secret audio recording without consent under circumstances that some people would try to claim are public.
For another example, there are restrictions on how you use that "no expectation of privacy", US-wide (e.g., commercial use of photographs, or cyberbullying).
And that's before we get into common decency, or arguable conflicting laws or principles.
But of course, every single time there is an opportunity for some new person to dismiss a good point with "no reasonable expectation of privacy!" such a new person materialize. And so someone else has to spend their time responding.
No, you can't film people in public restrooms, but that is an exception. There are limits to freedom of speech. You also can't yell "fire" in a crowded theater if there is no fire.
But yes, recording in public is generally very much allowed, and for good reason. I'm happy that we can film our govenment and dissemenate those recordings when they do something wrong. And that is the same first amendment right that gives government the ability to record too. And there are very few restrictions on recording, so yes, there is no REASONABLE expectation of privacy in public - the situations you outlined are all unreasonable. There are limits to free speech, but that doesn't mean recording in public isn't generally allowed.
It isn't "for whatever reason", it is part of the first amendment. Just because you don't like it doesn't mean it hasn't been the law for a very long time.