I suspect part of the difference is what kind of roads you are on. Whenever I'm in the Bay area (or Southern CA in general), I'm amazed by the quality of the roads. The pavement is even and smooth and the lines are crisp, fresh paint that is easy to see.

Meanwhile in the Midwest, we have potholes, uneven roads, sometimes roads with different surfaces mixed together (gray concrete with black asphalt patches). Lines are often badly worn by the weather and road salt and can be quite difficult to see.

I strongly suspect with no evidence that FSD likely has more problems on roads that are in poor condition.