I think in Germany a large part why Salaries are secret is because most people don't want to think about it.
https://www.quora.com/Why-is-everything-so-cheap-in-Germany
Also Norwegians probably do not have to look up their colleagues salaries, if they do not want to.
I would definitely like to know at least the general distribution.
If you earn right the median income , but think the actual median is much higher, you tend to not want to talk about your income because you are of low status, compared to everyone else who you expect to earn more.