household income != individual salary in many, if not most of the cases.

Right. Households often have multiple incomes. That doesn't help the OP's point, though, since people in Ohio are more likely to live in a multi-income household than people in California.

If you look at per capita income instead of household, Ohio gives $135,500/$26,937 ~= 5, and California gives $405,000/$30,441 = 13 By that standard, California is 2.6 times more expensive instead of only 2.