By class was referring to the economical status of some BH's citizens.
One persons financial class (middle income, etc)is relative to which area they might live in. 50 thousand per year in BH's is low. 50 thousand per year in rural Mississippi (second longest word I learned to spell in school..the first was my family name..26 letters) might be considered high. Mississippi is the poorest state in the union.
Eastern edges of BH's might be considered as a poorer area, all thing being relative.
Oh, I get it.