The fact that I make X here while pay is 4X in SF is the only proof needed to show job markets and pay levels are local.

If a SF company wants to hire me remotely, I'll take the job at 1.5X, so they won't pay more than that. The simple reason is this: If I don't want the job at 1.5X the local pay, I my neighbor does, and he's every bit as good an engineer as I am. When they do hire me at 1.5X my current pay, they have bought my skill at the local market rate.