Ironically nudity has become less common in Europe in part because of American influence. In Norway where I am from nudity used to be a very natural thing but American media/culture has a tendency to sexualize nudity and thus people become less comfortable with it.

It is not just about women but also children. Small children are usually naked on the beach in Norway. We did not dare let our kids do that when visiting the US as we saw nobody else letting their kids enjoy the beach naked.

As some Americans here pointed out, you don’t want to do things which makes everybody else in a culture notice and stare at you.

Of course it goes both ways. If you go to a Sauna and wear a swim suit then you would stick out like a sore thumb because being naked is the norm.

I don’t know how it is in the US, but in Norway there are big sauna centers with swimming pools, and a variety of saunas, even saunas with multiple floors, hot water, cold water. You don’t wear swim suit inside the center. Usually that is not allowed.