Liability could (and perhaps should) ...
... pass UP to the agency/body that licensed Uber to operate these vehicles on public roads without first ensuring that adequate safety protocols and controls were in effect to protect the public.
Superficially it seems like an absurd flaw in the system as described.
"Yes sir, our vehicles are perfectly able to recognise when emergency braking is required to avoid a potentially fatal collision when the vehicle is operating autonomously"
"Good, so there is no possibility that such a collision could occur ?"
"Well, not quite, because you see although the vehicle can determine that braking is needed, it won't actually apply the brakes when operating autonomously, but it will alert the safety driver who is then required to perform the emergency braking maneouvre, so it really depends on the safety driver being alert and their reaction time"
That should have been the end of the license hearing right there. Relying on a "safety driver", let alone one expected to have lightning fast reaction times, even if paying attention, in this situation is patently absurd since the circumstances under which the vehicle is going to NEED to alert the driver to the need for emergency braking are most likely to occur when the driver is NOT paying attention! For if they WERE paying attention then the need for emergency braking would almost certainly have been avoided long before it became necessary!
The fact they were allowed to operate without even this obviously ineffectual backstop operational only highlights further the negligence of the issuer of the license.
But, the license issuer being a state body and the operator being a Golden Boy "tech startup" means that it of course will have to be Joe Blow that takes the fall.