These unstated beliefs make up a lot of "Common Sense", which is reliably invoked as a means of outing someone for not being in the same "Tribe".

There's no such thing as "Common Sense", and every single niche, culture, demographic, etc has their own set of things that "Everyone knows"

I'm not sure why, but this feels like something Heinlein would have said. It's a solid point either way.