In your original post you mentioned clutter, which is I think a better example of what's difficult in driving: predicting the behavior of drivers and pedestrians. Even just processing the world into objects and deciding which ones might move is harder than seeing lanes in the dark, I think even for humans.

As for ice and snow, they produce more error, requiring larger distances between vehicles, but usually don't change the basic negative feedback mechanism, a mechanism that has been implemented by machines for centuries. The big problem with them is skidding, which is a completely different problem.