More importantly, I'd second "A fair salary is the one you shake hands on."
Interestingly, there may be an interesting relationship between the two observations.
We are located in Poland so the numbers are not exactly the same as they are for a US-based company, yet the structure is similar. However, some of the work we do goes through a partnership agency located in US. Some of the work we do directly for US customers. So these are the same people doing the same quality work with the same efficiency.
The difference in the rate for the end customer? 100%+ If they go through US-located partnership they pay double. Note: the whole setup is fully transparent for the end customer so there's no pretending that we are not who we really are.
Should our people expect better salary because there's someone making a huge premium on the top of what we are making? Well, that would definitely make our business unsustainable.
Can we raise our rates to a similar level when working directly with US-based customers? That doesn't work either as the premium is paid for the fact that people come through US-based consultancy.
Is the work done in any different manner? No, it's exactly the same work.
So we end up balancing our financials and we acknowledge that from time to time we would lose an engineer who will either jump on the independent consulting bandwagon (the leverage for them is potentially much bigger than if they were located in the US) or join US-based company remotely.
Ultimately "a fair salary is the one you shake hands on."
Note: we are an entirely transparent company, thus all the financial details are known to everyone and we openly discuss these matters. We also strive for fairness understood as collective fairness, i.e. if I want to earn over what is commonly perceived as the value I bring to the company I'm not getting it. Also, we share the profits with everyone at the company.