Workers should be paid what they are worth. The reality is that wages vary a lot. In my IT field, I’ve worked between two guys, one of whom was an absolute genius. He loved his work so much that he would have done it for free, which he almost was at $14,000 per year.
On the other side of me sat a lazy slob consultant at $200/hr charged with recommending the future direction of the company in IT. He did cut and paste from magazines without even reading the articles, and without giving credit to the original authors. He knew nothing about IT. But he sure knew how to BS, and how to negotiate a nice hourly rate.
(I was in the middle, both in rate, and in seating.)
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.