[riffraff]

> Maybe there are strong regional effects at play?

100% there are, plus age/cohort effcts. I grew up in central Italy and didn't know anyone who knew any dance, but by middle age caribbean dances (mostly salsa and bachata) became quite popular and every group of friends had a few folks taking classes and going to dance. There might have been a moment in time lambada was popular?.

When I moved to Hungary it turned out everyone had learned waltz in school or something (tho nobody would go out to dance it).