People can only walk so far especially if the weather is bad, they are older, etc. The point is if I have to walk past multiple gas stations and a car service center with broken down cars and fumes then it’s not a nice place to walk. I have lived next to a car service center before and even though it was tiny it was a constant blight on the neighborhood.
Not to mention almost all the grocery stores in San Rafael are east of the highway while the Google-labeled walkable areas are west of the highway. So in practice people probably don’t walk to the grocery store on a regular basis unless they go to the Safeway. You may have a different view but Safeway is a terrible grocery store by Bay Area standards so it’d be a real shame for that to be your only realistic option without resorting to bus rides.
Bus transit is less reliable than metro for a number of reasons, most notably getting stuck in traffic. It’s fine if it works for your particular usage pattern but a bus that runs once an hour and doesn’t have an exact arrival time isn’t the most convenient. I’d much rather have a metro that comes every couple minutes like almost every major city in Europe and Asia.
You seem to hate BART but I’m not really sure why and why you believe the cities outside the North Bay are full of lawbreakers. San Mateo has a higher household income and SF is tied with Marin. Marin is just full of more NIMBYs. It’s not like their shit doesn’t smell just because they live in a less populated county.
As for why I focus on public transit, it’s because you can only walk so far before you need another mode of transit. If you don’t find a convenient one, then most likely you’ll take a car. If people take cars a lot, then the city will be designed to support those cars which makes it harder to walk. Then fewer people can reasonably walk to all their needs so even more people buy cars creating induced demand as the highways and roads constantly need to be widened over the decades.
Maybe you’re happy with a tiny little downtown like those in most of the Marin cities but for most people from a major city they would be bored with what they could easily explore on foot in one of those towns in probably a few weeks. Without a way to connect to other cities, you’re basically just trapped in a tiny little area without resorting to once an hour bus service and cars.