Per your example, $6,000,000,000 of revenue generated by 100,000 employees works out to $60,000.00 worth of revenue per employee.

$400,000,000 of revenue generated by 3,000 employees, on the other hand, is $133,333.33 per head.

But maybe that logic is flawed. Since we are just talking about pilots, let's try dividing revenue by approximate pilot group size, again using your example:

UAL: $6,000,000,000 ÷ 13,000 = $461,538.46
K4: $400,000,000 ÷ 800 = $500,000.00

It is also worth noting that there are considerably smaller well-paid pilot groups at corporate flight operations that generate an order of magnitude less revenue than what we're talking about, and they throw the math even further. I had the privilege of flying for one overseas while the US airline industry went through a decade or so of soul-searching. In those deeply unfair times, many of us made more than the widebody captains that flew us back and forth to recurrent Stateside.

There may be plenty of reasons why Kalitta does not have an industry-leading contract, but presenting your logic as though it is a hard and fast rule of business suggests a need to examine the issue further. As others have said, employers pay what they need to. The recent behavior of the company suggests that Contract 2021 is no longer sufficient in their eyes, either.