The weather problem needs to be solved if you want fully autonomous vehicles with no human on standby, otherwise when it snows you'd have a bunch of autonomous vehicles stood still, blocking the road not knowing what to do.
There are tens of millions of US customers who live in areas that never receive snow and rarely receive rain. It's clear there are a few different technical solutions, and probably the engineers working on these problems will think of a few more in the next decade, if it's a major challenge SDCs will just be targeted at minimal weather markets to start out.