“In theory - no business can deny general service to anyone.”
I have never heard that. May I see your data?
I know that protected classes can’t be denied service, but I don’t know of any theory that would legally prevent a conservative elected official from being asked to leave a restaurant owned by a liberal.
It’s called public accommodation laws which vary state by state but generally state that you can’t deny services if you’re a public business on reasonable grounds.
The civil rights act goes above and beyond this - not just for public acccomodations but also for things like housing and schooling.
It’s to stop the whole “we don’t serve your kind here” mentality.
Private businesses/clubs were always exempted by these laws… until courts found they weren’t.