If you want a house in or that has access to the trendy area of Seattle, be prepared to cough up anywhere from $300,000 to $600,000 (median is $619k but I assume some folks will buy a smaller house or one that needs a bunch of work to get the price down).
Texas has bad schools, high Crome, dumpster divers everywhere. Washington state is a first world country in comparison. Even some boondocks place like Spokane where houses still go for $150k compares well to Texas (though the tech jobs are all in Seattle).
You're 100% right that you can find cheaper housing in Auburn, Federal Way (mind the gunshots), Everett, or even Spokane. The problem is that living in none of those places gets you the walkable, diverse lifestyle of being in Seattle.
Also, thanks for painting all Texas schools with such a broad brush. I graduated from a north Texas (public, non-charter) high school that is well-ranked, in addition to graduating from a state college for my CSCI degree. My siblings came after me through the same school, one as recently as 5 years ago, and none of us are drooling founts of stupidity who can barely sign our own names. It's almost as though different areas have different levels of achievement in their schools.
The Texas school, conversely, was a palace of education. Better in every way. Highly-paid teachers, actual funding for extracurriculars, buildings that weren't condemned. Four years of computer science classes.
Are there bad schools in Texas? Absolutely. But the fact is (unfair as it may be) that in the areas a software developer is likely to live, the schools are fantastic.