I had the same experience even in Santa Clara County. Google maps led me to drive on unpaved roads along the farms near Gilroy in order to avoid the congested 101. It's not worthwhile, and I'd argue Google should expose an option to let me express my preference.
We probably shouldn't be surprised that a navigation app that tells you to make left turns during rush hour in San Francisco doesn't behave any more rationally in rural areas that aren't a stone's throw away from the company's own headquarters.
Being able to express your preference isn't what Google is all about. Their attitude is that they know best.
