I agree that fair is irrelevant, but my point is that the supply and demand dynamic is different in the remote situation.

Indeed, if all companies went full remote overnight, the demand wouldn't change that much, whereas the supply would be much larger.

If the company doesn't expect the employees to be physically present in a given location, the supply of talent is increased since it isn't restricted to a given area anymore.

So while I understand that people living in SF wouldn't appreciate having their salaries cut to the level of [low COL city], I don't see how companies would continue to pay SF rates when they can access talent for a lower price just because they live someplace else. And said talent could even be the same exact SF engineer deciding to live someplace else for personal reasons.