I don't know that anyone contents that payments should be equally distributed. I think most logical people understand that a CEO should be paid more than a cashier.
However, I do think that over the course of the last 50 years, the difference between what a cashier is paid, and what a CEO is paid, has widened to a point that is ridiculous. Since the 1970s, CEO salaries have risen over 900%, while worker's salaries have risen 11%.
Even given the more complex job of being a CEO in the modern world, how is this inequity fair? If a CEO is doing his job, and his company is making a profit, shouldn't his workers be seeing higher salaries, as well? It seems as though more often, the profit goes to those at the top, and nothing makes it down to the workers. In contrast, when a CEO does a bad job, the workers are often the first to suffer, with cuts in hours and pay, or loss of employment, while the bad CEO is given a huge severance package.
50 years ago, a worker on the lowest end of the pay scale could still feed their family, and consider saving up for a home. Today, those lowest workers have to ask for government assistance just to keep food on their tables. Meanwhile, the big bosses are raking in the bonuses, stock options, and huge salaries. Does this seem fair to you? Does it seem logical to reward people for underpaying their workers?
I think that's the equality issue here. Not that everyone should be paid equally, but that everyone should be paid in equal proportion to their contribution to the company. Right now, that payment is way out of balance.