Earlier quoted context omitted.
If uber drivers make enough to make their cars a worthwile investment, then I'd assume a fleet of driverless cars are profitable.
Uber drivers use their cars for stuff other than Uber. It's a way to make additional money from something you already have. That would not be the case if Uber had its own fleet.
If I own a self-driving car that sits in my garage from 8 PM to 8 AM, why not just put it on the Uber network and have it make money while I sleep?
As long as people still own cars, why does Uber ever need to own their own fleet? If anything without the actual pain-in-the-ass of actually having to be a driver, I'd think a lot more people would crowdsource their idle vehicles.