can it really be "best" if you're treated unequally just because live somewhere different?
For some people, sure! There are dozens of other metrics that can be used to evaluate a remote work environment, and for a lot of people "my salary matches my coworkers" doesn't matter as long as it's a good wage relative to what they'd be able to get working in an office locally.
You stance seems to be you can't be the best unless you do _everything_ better than everyone else.
Gitlab might not be a world leader in salaries, but they might very well be a world leader in providing the best remote work environment to their employees.