It’s always a bit problematic to compare SF County to other counties like LA. SF City and County are the same geographical area where, Los Angles City and Los Angeles county are not. LA county includes 60+ suburbs. Santa Clara county has San Jose metro but also 14 suburbs.

Put it this way LA county is 4000 square miles, Santa Clara is 1300. San Francisco is 47. I bet if you target the most urban areas of those counties the numbers get a lot closer.