Self-driving is so far out as a door-to-door taxi service as to be utterly irrelevant to Uber's business model.
Customers want reliable transportation. Imagine if your internet company could only provide service when the weather was good. You'd quickly switch to the service that is reliable because being without service becomes unimaginable. This is especially important if you want to compete with car ownership and not just livery services. These companies also need to be reliable on pickup times. If a service take 5 minutes sometimes and 25 minutes at other times, most people will give up on them and go for the 5 minutes all the time service.
What could Uber today with the resources being devoted to automated cars? Could the app be improved, could the route optimization algorithm be improved to create more ride shares? I and you won't know because those resources are going towards a different agenda today.