Its not about the money, its about what the money can buy. You even said it yourself with your last line:
This means that for almost all of CA, a $100k/year household income is sufficient to live a VERY solid upper-middle-class to middle-upper-class living.
100k/year in a place like Alabama affords you a 4,000sqft home within 30 minutes from best jobs and economic centers in the state. If you live in other areas in Alabama, people can afford a good middle class living on $50k/year and even less if youre smart. Support positions that don't require physical presence are frequently moved from CA to the east coast and the cost savings is on the order of 30-50% simply because of the cost of living adjustment. That's why Wells Fargo kept so many jobs in Charlotte, NC when it absorbed Wachovia.
Your income tax analysis is dishonest and lacks understanding. The CA income tax hits 8% at $60k, which can't buy jack in CA, for most citizens its at 9.3%, double the AL income tax rate. If you make under $30,000, you pay less income tax than someone who lives in AL making that amount...but you also have to pay 1% for mandatory SDI up to ~$100k, making up the difference.
BTW, for item #1 in your list, PA has a flat income tax. Why do I know all this stuff? I do it for a living. CA, NJ, and NY are the most expensive places to operate a business and have the highest cost of living adjustments, bar none.