>What happens to the guy in open salary co who is legit 50% better than everyone else?

The GP is right in that, that person doesn't have much choice but to move on.

I don't have experience with open salaries but I do have experience with collective agreements and seniority. They aren't meant to take into consideration the "super stars". That's not what they are meant to do. Seniority and collective agreements do suck if you're a "super star".

I don't think there's a system where everyone is a winner.