Having colleagues that lived there and moved elsewhere. You are correct not everything is double. The (3) main components of living costs (Transportation/Shelter/ Necessities) are a cross-the-board significantly higher. Not exactly double. Now for that role he took, the market rate for that area isn't that attractive that's why no qualified locals were applying. Hence why they got an outsider who looked at the 300k and automatically assumed he would be way better off. Not always the case.

There's factors I know certain areas in California are cheaper and better for certain industries. For the industry that he is in wasn't worth it (Non-Tech) Now I can see why some people who aren't earning higher wages can't see themselves rejecting a 300k job offer. But there's a reason locals that were qualified were asking for more… hence picking an outsider… (less money asking)