What makes you confident about that? I only see evidence to the contrary. Having workers able to see what other jobs are paying might encourage them to make moves to increase compensation.
Hiding the numbers makes it less obvious if one is being taken advantage of, which is a reason employers have made it taboo to discuss pay.
Posting wages might make it easier for companies to match their offers to others, leading to a sort of collusion, and salary stagnation.
Posting wages might make it easier for companies to offer higher than others in an attempt to attract talent, leading to competition in the market, and salary inflation.
I suspect that different things will happen in different markets. It seems (to me) that software development may be unaffected, administrative workers might benefit, and unskilled workers may suffer.
As if that hasn't already happened
https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_L...