Earlier quoted context omitted.
How can you determine market pay when salaries are private? You end up with what we have now: looking at what companies post publicly for salary offers. Some companies don't publish those numbers publicly, and that's only 'new hire' salaries. So it's inaccurate.
You as the employee with that skill DETERMINE the market value. If every IOS developer refuses to work for $40k and want $80k the market will start having to pay $80k. Yeah there will be outliers, maybe someone desperate for a chance to prove themselves, or someone who was unemployed will take that $40k but that is not the market value. It's not some vooodoo a company makes up, you yourself have a direct affect on th…
Basically, keeping information private gives an advantage to the people who know the private info versus people who don't. If no information is private, that edge is lost, aka, a more level playing field.