I dislike how transplants tend to broadly paint the East Bay. It isn't a cheap region either.
Most blue collar labor types living in the East Bay are in the Alameda County flatlands (parts of Newark, parts of Fremont, inner city Oakland, Berkeley, El Cerrito, Albany) or North Contra Costa County (Pittsburg, Antioch, Richmond).
But most of the unskillled labor underclass you see in the Bay Area cities tend to drive in/Bart in/ACE in from San Joaquin Country, Sonoma County, or Monterey County.