Those would in many cases be the same company. And yes, the entity responsible for injury would be the car manufacturer, not the driver or riders. Taking on legal liability for the car is part of the 'qualifications' for L3.
The specifics of what part of the system failed can be litigated if defendants (companies) need to be added to the case but in no case will the people inside of a vehicle designated higher than SAE L3 be held at fault for the accident.
For self-driving, that evaluation is almost impossible. Sure it can look good statistically, but for things like brake lines, brake pad material, brake boosters, etc, they are governed by the laws of physics which are more understandable than any self-driving algorithm.