I know by your handle this is going to fall on deaf ears but:
Your theoretical example is perfectly logical. Unfortunately I'm having a hard time transferring it to a real world example in my company, or other companies.
Now if one person made oranges and the other made gold bars it would make perfect sense. But people don't "make" oranges. They pick them. Or they plant them. Or they tell people when to pick them or plant them. Or they supervise people who tell other people when to pick or plant or water them. A little more complicated now right?
What people produce isn't really goods, it is "work" that is added to things to make them more valuable. Turning a lump of clay into a statue. Turning libraries and code into programs. Turning ore into metal. Turning disparate data into a useful statistical analysis for the rest of the company.
Unless you're talking about yesteryear artisans and craftsmen, you're going to be hard pressed to find a person who completely produces a good with no help. In fact, some would say the whole point of modern industrialization is that we take complicated things and break them down so we can move any person around and still produce the same good.
And when the production isn't an assembly line anymore and becomes this complex web of people who do jobs which effects are near impossible to quantify, well I would say hugely differing salaries are not as defensible. Plus having this "artificial" limit tells the employees that if there is a rising tide, it will raise all ships. People like fairness and equality and the feeling that someone gives a damn about you and if this policy accomplishes that, good for them.