If a man was making a real income of $95k in 1980, and was then knocked down to $55k, so his wife raises their 1 kid (as the example given), goes back to work and makes $100k - they have moved from middle class to upper middle class.

Interesting these charts start in 1980 as well. The average real hourly wage went down from 1972 to 1980, then began a recovery. So when you don't show things were better beforehand, it looks like a constant rise, which it was not.