Yep, that’s exactly true. It wouldn’t have actually helped (much) in preventing the accident, even if it might have made the drivers more alert - or at least try to be more alert. A situation where drivers have to respond (instantly) to a rare event when they otherwise don’t have to do anything is a losing dynamic to start with. Uber just didn’t do anyone any favors by having the drivers ignorant as to how it was all set up, though. The system was broken by design in multiple ways, and having a human being “take responsibility” was absurd because they couldn’t be responsible in that situation.
It would be a total disaster - you either have drivers who need to fully drive the vehicle, or you have fully autonomous vehicles. Anything in the middle just doesn’t work and shouldn’t even be considered. Anything less than fully autonomous vehicles should only be implemented as safety backups for drivers - which means ironically, just for safety’s sake, drivers have to end up doing driving tasks that the vehicle is perfectly capable of doing itself, just to keep them engaged.