Really? By your logic Minnesota, Iowa, North Dakota, South Dakota, Colorado, Montana, Idaho, Wisconsin, etc. should shut down for the winter?
Businesses don't shut down just because the forecast says it might snow. Plows can't get out fast enough to clear the road to a point the lines would be readable/visible for a self-driving car. Humans may not be perfect but we find a way to get home in the snow without the massive casualties you're implying should be happening.
Most drivers don’t live in Minnesota, Iowa, North Dakota, South Dakota, Colorado, Montana, Idaho, Wisconsin, etc. If you want to see how the average driver performs on icy roads, look at videos from Portland and Seattle. Both of those cities practically shut down when there is snow on the roads.
Businesses don't shut down just because the forecast says it might snow. Plows can't get out fast enough to clear the road to a point the lines would be readable/visible for a self-driving car. Humans may not be perfect but we find a way to get home in the snow without the massive casualties you're implying should be happening.