It probably comes down to pride. Americans are a prideful people, we don't like to admit to being wrong or inferior. If you go around telling all of your coworkers how much you make, chances are good that at least one of them is making quite a bit more for what you see as the same job. Most people would rather not find out that they get inferior pay to their coworkers, even if they could potentially do something about it, because it tells them that the employer sees them as the one worth less (whether justified or not).

It's kind of like how most people aren't going to just ask their spouse if they're cheating, they'll wait until the evidence is clear. Nobody wants to confront the potentially ugly truth.

> Most people would rather not find out that they get inferior pay to their coworkers, even if they could potentially do something about it, because it tells them that the employer sees them as the one worth less (whether justified or not).

I don't think you can actually assert that this is what people actually want on a meaningful psychological level. They're certainly scared away from doing it with unenforceable lines banning it in contracts, TV shows skirting away from mentioning salary figures at all times, etc.

The word taboo is fitting precisely because of this.

I'm not saying that people want to be secretive about their own salary, I'm saying people are afraid to know the salaries of their peers.

To use a childish simile, it's just like how most guys won't actually say how big their dick is, even if they'll talk about the general topic. It's not because it's "taboo", it's because they don't want to find out that their best friend is bigger.

I'd say it is consonant with it. Making salaries public has a strong flattening effect - it makes it much more difficult for people of the same rank to have different pay. Someone else said in Norway all salaries are public, which fits the Scandinavian idea that one person shouldn't be much wealthier than another. In America, there has traditionally been the idea that you as an individual might be able to get rich.

I'm not taking a position on which side is better or worse, just noting that whether you aim to get richer than your neighbour is probably going to be the main thing determining whether you think salaries should be public or private.