> let's say you go for it because it's essential to the success of your project, you might end up having to pay someone 3-4 time his "market" value, making it unfair to his "locally hired" colleague that have the same amount of experience and responsibilities, but don't have the right profile for a specific project.

If you are critical to an important project you get paid significantly more. How is that unfair?

That's the system working as intended.