Baths and saunas

Finland has roughly 3.2 million saunas for a population of about 5.5 million, and in December 2020 UNESCO added Finnish sauna culture to its representative list of intangible cultural heritage. Over roughly the same period, public bathhouses in Korea fell from 9,919 to 6,012 and Japan's sento dropped from a 1968 peak of 17,999 to 1,562. The heat is the same everywhere. What differs is the rules around it.