Assuming interchangeable human resources there are basically 2 options, either the company is extracting more value from everyone than the salaries they pay, in that case paying fairly would eat into the company's bottom line. Poor CXOs would not turn extra profits by keeping less fortunate employees on low salaries but just the regular one. Or the highest paid employees are not pulling their weight and their salaries are already subsidized by the rest of the company, which is also not quite fair.

Nevertheless, I agree everyone looks at this problem from their own POV, however it should not be the norm to provide equal compensation for equal work.