No it isn't. You're doing the same work. It is fair to get paid the same for the same work.

Do people pay plumbers the same in SF as they do in Charlotte?

As an employee I want to be paid the highest that anyone else is paid for the same work. More so if the value generated is the same regardless of location. Yet I can understand employers wanting to help maintain sustainable communities, even where cost of living is high.

Governments too want some control over their currencies and its value.

I don't desperately need to have understanding for governments or corporations. They can all take care of themselves without my help.

My point is it's a collective concern too. Because without coordinating all prices globally there will be variance in costs of living. Which could price out lower valued jobs from certain areas entirely.

I live in Silicon Valley and had to pay a plumber 150USD just to visit and fix a small problem. Do you pay a plumber in your area 150USD (in local currency) for 30min of work? If not, why not?

Yes in Denmark it can be even higher than this. So Danes are being compensated (it's actually much less than SV programmers: I'm getting a take home of 81k a year for senior) but are paying more for plumbers.

This is one hundred percent a problem of exploitation and cultural expectations and needs to change.