I have a first-hand experience with two countries, Slovakia and the UK. I also have a second-hand experience - through relatives living there - with three more: Czechia, Italy and Ukraine. And it is the same everywhere. No one talks about their salaries except with their spouse and, sometimes, close friends. The Ukrainian contact is the most secretive.
I am in two minds about openness of such kind. I can see the potential benefits but also the drawbacks, as exemplified by the recent furore about the "pay gaps" in various organizations. People tend to focus on how much more Jack earns than Mary but somehow forget the tiny details such as how much more Jack gives to the company, how much more overtime he works, or, in case of celebrities like actors and tennis players, how many more crowds he brings in. In short, I agree that person X and pesron Y shoud get the same amount of money for the same amount of work. The tricky bit is proving they do the same amount of work.