I worked for a public university in America, therefore being a public employee. Any of my neighbors could easily go to the state website and look up my income.
Frankly, I never felt that to be an issue. It was also nice to have that transparency in the workplace, all of my colleagues knew exactly how much any of us made.
The press will publish all the highest earners in various segments, areas etc. So in the small municipality I'm from I'm used to the salaries and net worth of all the local business owners being in the newspaper.
In addition one can online search for whoever you want. Later years, one has to log in to check, and then the other person can see who have viewed their information. This has probably cooled it a bit. But can just get someone else to check for you..
This isn't a total cultural norm, if anything I think it's a view from america a few generations ago. For instance all of my friends and extended friend groups are open about our incomes.
With complete total strangers I would totally agree people generally don't lead with their salary. But after knowing people for a while it's come up a bunch and it's a taboo.
As a added point, the system in Norway was fully open up to a few years back.
They have since changed it in a way that you need to login to lookup other people income and the person in cause then gets notified of whom looked it up. So that typically could end up in an ackward look from/towards your neighbors .
As I understand it, you can also see exactly who has looked up your salary info, so it might make for some awkward conversations if your neighbour did search for you.
Frankly, I never felt that to be an issue. It was also nice to have that transparency in the workplace, all of my colleagues knew exactly how much any of us made.