Why is the kanji 床 (floor) used to talk about a barbershop?
According to some answers in the post linked in the comments, here's two possible explanations.
- Originally barbershop had tatamis (this isn't really thorough, many places had tatamis).
- Quoting: "There was a barbershop in the Edo period that had a tokonoma; people referred to it as 「床の間のある店」(the shop with the tokonoma)". This is also a possible explanation.
Maybe an expert in history and linguistics can pinpoint references of the origin of this word?