it's literally because they are told to do so. (it has also leaked a bit into the german-speaking part of switz, so i know how it works) that's all there is to it. they are told to do it, and they just do it. it's not like it was an autonomous decision or a gradual popularization. it's just plain signs that say "sit". this, almost above the whole covid vaxx saga, proved to me how much people are rule-following npcs without an own internal life.
Switzerland