The problem is that it cannot be defined outside of ethical perspective. Workers same way as employers and others are human beings and it is the benefit of the actual human beings which is the right objective. No sophistry can hide this fundamental fact.
I believe that as much as material prosperity is good as much the higher wages and profits are good.
A worker is worth what a willing and able seller of his services and a willing and able buyer of his services agree on to be the value.
That definition is simple and the ultimate in ethics. By what right does some politician or bureaucrat (or other) have the moral and ethical right to impose what that price should be without the willing consent of the parties invovled?
Now I work for a consulting firm. I williningly delegate to them the power to negotiate my wage on my behalf. Some (but not all) of my union member friends willingly delegate to the union the power on their behalf. Likewise, the stockholders or other owners of a company willingly delegate to management the ability to negotiate the wage on behalf of the stockholders.
The problem comes in when some elitist/idealist thinks that he is superior than us poor slobs and that due to his superior moral, political or technocratic insight, he should on my (or you) his enlightened view of what we do not willingly do.
Is the free market perfect? Hell no. There are individual anecdotal situations where it definitely is not. But overall, it is far better than leaving decisions to the elitists who end up more interested in their own power, than in altruism.