But you wouldn't have access to the whole market, because you'd be missing out on people in the major tech hubs. And as it turns out, much of the best talent in the world is clustered in those tech hubs.

But the candidate doesn't have that many options so they have to put up with what they can get. It's thw law of offer and demand.

That's not really true. As a remote developer, my employer is evaluating me against all other remote developers and their compensation. I'm evaluating my employer against all other employers offering remote positions.

Sure, the employer has more power in that negotiation, but it's not like there aren't others out there.

Your English is good. :)

You only have access to the subset of the market that offers remote employment.

"Market" in this context means employees, not employers. The subset of employees completely disinterested in remote work is presumably much smaller than the subset of employers disinterested in offering it.