Seattle is pretty expensive, and while Portland is much cheaper, it is still more expensive than Austin. I would love to be in either of these places, the Austin heat is not for me, but I've never been able to get parity on CoL from job offers there and honestly that's all that matters to me right now.
Washington has no income tax, which like Texas is a big help, but you still can't beat Texas. Oregon has no sales tax, which is less valuable and likely offset by depending more heavily on income tax. I can see why these places may not have made the list.
However if you lose your job in Texas, you are basically shit out of luck. So it's NOT a great place to come to try out a start-up where cobra may not exist, and where the ACA is laughed at. It's only good for big, established companies.