Roads at the time the series is set were not commonly painted in the modern fashion (double yellow "no passing" center lines and white lines along the shoulders).
During the entire first season, the location of Lucia seems to be inconsistent with the actual location in the real world. There are several mentions of driving "down" to Monterey, with shots of cars driving south along the coast, when Monterey is actually north of Lucia. Gwendolyn occasionally seems to travel relatively quickly from her job (and presumably home) in Sacramento to Lucia, despite the drive from one to the other being over 200 miles.