As far as I can tell, every human culture has some taboos about these things. In my readings, I've never heard of a culture where the base state is nudity and this is unremarkable. Even in cultures where we think they're nude, they're still working their own modesty standards. I am reminded how in some traditional New Guinean cultures, the males wear nothing but a gourd to cover the genitalia. But they're very shy without the gourds. Similarly, there isn't a single culture ever documented (to the best of my knowledge) where lovers don't usually seek some degree of privacy.

Of course, exactly what counts as nude (or public lovemaking) and just how draconian the repercussions for transgression are, varies greatly.