in the tech job market generally, the value of the work to the company puts an upper bar on a salary, but competition with other employers for the same worker puts a lower bar on salary (obviously along with other factors like the company's reputation, mission, benefits). In practice all salaries are set by the latter rule, which means they depend on the job market, which varies by location. That salaries should not depend on location is a fantasy based on some weird idea of people getting "paid what they deserve"—a fallacious association between your salary and your worth as a person, which people would do well to get over.
It’s only a global market if there’s a meaningful number of employers treating it as one. From what I’ve seen, and what the comments on this post have been able to show, such employers seem few and far between.
The price of Coke is influenced by logistics but ultimately it's determined by the market (supply and demand), exactly the same as your work, that's capitalism.
What's the market in this context is of course the interesting question.
The market for Coca-Cola is very different from that of software programming labour: Soda pop can only be consumed where it is actually located, so is affected by, as you pointed out, logistics and (local!) supply and demand.
Remote programming work, on the other hand, is the opposite: At least the demand side is, as this whole discussion exemplifies, global -- Gitlab isn't local to all the locations where their remote employees live. (If it were, they wouldn't be remote.)
But then the employees' supply of labour isn't local either: They're offering their labour to Gitlab, a non-local employer (and potentially to other non-local employers too).
It's utterly baffling how much of this discussion seems to be assuming that Gitlab (or other remote employers) play on a global market, but their employees on a local one. If that were the case, how could any of those employees ever be employed by any of these employers? The very fact that any transactions -- i.e. employment contracts -- ever arise shows that both parties are playing on the same market.