It doesn't make sense that top people return many times what the average does but you are only able to pay them 50% more. That kind of thinking is why salary ranges should be posted before top people waste their time applying.
I completely agree that it doesn't make sense, but that's how it is. Anyone who's ever hired a top performer will feel like they're getting the biggest bargain ever. I guess that psychology artificially limits the top of the range for salaries.