Fairness is an issue for Kindergartners. Anyone that thinks that life is fair has a single digit IQ. Any piece of legislation with the word fair or fairness ignores reality.
A third party, be it a union or government, has no place in determining the value of an employee. Every employee has a level of talent that rates a level of compensation. The idea that a union or government can establish pay scales make no more sense than having them decide who you should marry or divorce.
It’s a two way street, employers don’t want to loose an employee because they are under paid. Employees that have a talent for sale can sell it where someone is willing to pay for it.