The value of information can be calculated in multiple ways, from multiple viewpoints.
“My Boss Makes What? (Employees Work Harder If They Know),” The Wall Street Journal, August 6, 2018 R1. Salary transparency makes people work harder.
Is what you make “private”? Should it be? Whose interests are served by keeping this information private? Who owns it, you or your employer? Do anyone have a duty to keep this private? Why would your employer want this kept quiet? To avoid Sally complaining that she works harder/better/faster/quieter than Sue, and should be paid more? Or to keep a competitor enticing Sally away?
Ask yourself why you want to keep your salary private. Sure, you don’t want marketing agencies targeting you because you’re wealthy, but they probably can approximate your salary anyway.