For clarification purposes, Millbrae is a suburb of SF, not a San Francisco neighborhood.
I was born in Milbrae in 1952. Recently I did a Google street view of that house. It is NOT what I would call an affluent neighborhood. I assume it is not the neighborhood referred to in this story. OTOH, housing costs what they are, maybe a working class street is considered affluent.
My neighborhood in small town Kentucky looks much, much nicer and it is not labeled “affluent”. Just middle class.