The point being, as we've moved to the two incomes per household standard the price of things driven by demand (e.g., housing) has also naturally increased.
In those 8 urban areas compensation is higher. It's not advance economics to understand that housing - especially when supply is limited* - is going to increase. And as a percentage of the entire population, these are outliers. We always have outliers.
All that said, the better question is: As a percentage of salaries, which areas are most the most expensive?
* There's a cost to NIMBY and these communities seem to be okay with that.