You're overthinking. Fault is a legal construct to help decide liability. What we really care about is if we're dead or not. Insurance is there to take care of

You're overthinking. Fault is a legal construct to help decide liability. What we really care about is if we're dead or not. Insurance is there to take care of the rest. Since drivers under the influence are less likely to die in an accident because most drugs either relax the muscles or delay reflexes enough to keep the body relaxed during an accident, preventing a lot of potential injury, it's an important nuance to consider. If the people most likely to drive drunk are the least likely to adopt self driving cars, there is an absolute floor to how much safer they can be.