But prices aren't based on fairness, they are based on demand and supply. If there is a supply of workers willing to work at a lower price in areas outside of San Francisco, then it makes sense for a company to purchase their cheaper labor if it supplies the same value as the more expensive labor.
> But prices aren't based on fairness, they are based on demand and supply
If they were based on supply and demand, locality of seller would have no effect on the price buyers were willing to pay for goods that aren't location-sensitive, e.g., remote work, because it's not a location-bound market and goods would trade at the global market clearing price absent (inefficient) artificial market segmentation that is only possible (for buyers) when there is an effective monopsony for the particular good/service being purchased (since competition would exploit the underpriced segments buy buying up what they are selling at a price above what the attempted segmenter was offering.)
That may very well happen over time. Non-Bay workers may bid down the price of coding labor, and remote workers from disparate markets will bid against each other, and eventually some "global market clearing price" may be established. Economic theory doesn't operate instantaneously, though. It manifests over time as individual actors bid and negotiate. Remote work is relatively new and its substitutability is being figured out. In the meantime companies may exploit the inefficiencies (and so might workers).