- Companies (or, if you prefer, the very rich people) actively discourage sharing the salary information; the monopoly of this information is a huge financial benefit to them.
- Employees are either indifferent to "politics", that is to shaping the system by which the civilization runs today, or they support the current one.
I wrote a rather long diatribe expanding these points, but it grew so bitter I decided not to share it.
The observation which could escape many readers: publicly known salaries give a great power to employees to get more money from the employer.
Some say that secret salary negotiations are advantageous to the most powerful employees. Are they? Well, the power of these employees is quite soft: knowledge, skill, experience, relations, performance.
Publicly known salaries could lead to the public salary negotiations, which could then lead to collective negotiations (think trade unions). What is the negotiating power of a whole team? Humongous. Just for starters it trivially includes the soft power of the team's top employee (the same knowledge, skill, experience, relations, performance that a top employee could use in secret negotiations). Now combine it with the soft powers of all other team members. Now add the hard power: "we are yet to see if our entire team could continue to work inside this organization".
This illustrates how even the top performer can expect some gain, while it's true that the mediocre performer gets relatively more.