Odd, I have family who have lived in the bay area for over 50 years and use "the." Now if a character had said "Frisco," then yes, I'd say that was a dumb mistake as every San Franciscan hates "Frisco."We usually say "crushing down hwy 101." And I've lived in the Bay Area my entire life. Never heard anyone put "the" in front. And if they do, I ask if they are from SoCal, and the answer is usually yes. But I guess it isn't impossible for someone to put "the" in front. It's just very rare. Very very rare.