Because we have structured society and our culture in such a way that some people can only feel safe when inside a small thick wall cell with the door locked behind them. That's terrible though, my proposition is to invert that, what would allow people to sing in the streets without any fear of judgement, and use that as a basis. Privacy as an idea suggests "let's put more doors with locks" when in fact that doesn't help at all. It doesn't address the problem that necessitates those doors with locks to exist.