For example, a train of self driving trucks can be led by 1 in the front. Yes, I know, REAL trains exist, but they don't go everywhere. A train of self driving trucks could save a lot of money.
If self driving Taxis don't work in the rain, then Uber can just NOT drive them when it is raining! For example, Maybe the penetration rate will be very low in Seattle, but very high in Texas. Disrupting 20% of the Taxi market by eliminating drivers is still a very big deal.
And for trucks, will you let supermarkets go dry once it starts raining? Otherwise you need to keep drivers on retainer. And then you might as well just have them drive for minimum wage.
When it is sunny, the self driving cars are out and about, and the price is low.
When it is raining, the self driving cars stop taking passengers, and the price goes up, with surge pricing, which is handled by human drivers.
You don't keep drivers on retainer. You simply publish the price, and if the drivers like the price, then they can accept the job. If not, then they don't. If there is a shortage, then you use surge pricing until the shortage no longer exists at the given price point.
For trucks and supermarkets, if it is raining then you pay human drivers. If not, then self driving. BAM, labor costs have gone down by 50%.
Uber doesn't have any interest in self driving cars succeeding. It's a PR distraction to justify the exploitation of drivers ("you shouldn't complain because you are lucky to have a job at all when self driving cars are coming any day now").
Self driving cars that don't have drivers would completely destroy Uber's actual business model which is based on undercutting current taxi companies by shifting the capital, maintenance and insurance costs onto the drivers.
Think about what you're saying here. If manual driving is still required 60% of the time there will still be mass-unemployment of taxi and truck drivers. These guys are not paid well enough that they can afford half the amount of income that they currently have.
The hype right now is so great that even if the reality is amazing it will be disappointing.