Remember that the needed salary and the typical salary don't change at the same rate. Going from his place to mine, that equalizes things for roughly a 20% savings rate.

Somebody earning $200,000 in San Francisco who moved to Seattle would gain an extra $33,558 in disposable income, despite income dropping to $142,858. This is because costs drop to $176,414. To equalize the savings in dollars, the rate would need to be 59%. Is that person in San Francisco going to save 59% of their income? If not, they'd be better off in Seattle. Of course, Seattle itself is not cheap, and you can do much better.

And yes, there are other considerations, like being able to afford 3500-square-foot house on 5 acres of land and still get to work in under 20 minutes.

The cost of living has, baked into it, a sort of normal-for-the-area lifestyle. It is simply expected that less-urban people will have larger houses on larger lots.