I believe the author would argue that these 'middle class' Valley engineers really aren't middle class at all, but rather upper class. They're likely up in the 95th percentile of earners. Though I struggle to come to terms with how to control for living costs and geographic inflationary trends. I would like to see an accounting of how wages across the employment spectrum are adjusted, as well.

In my mind, if wages for other forms of employment aren't similarly inflated, it makes a much stronger argument for a further bifurcated society.