Regulation like this would be absurd considering anyone can legally publish their salary publicly. Salaries are not public because employees want them not to be public.

I don't want lawmakers or trade unions undermining my right to privacy under some manipulative power-play guise of "fairness". We are all free to make our salaries public, if we think it is in our best interest to do so, let's talk about and focus on that and not be so naive as to believe regulations will magically solve a cultural issue.