Your thought experiment doesn't work. I wouldn't accept any position where my family members die and beyond that, it's immaterial to the scope of discussion.
Let's examine various different scenarios under which someone dies in a car accident.
human driver was negligent and causes a fatal car accident.
Human gets criminal charges. Insurance pays out depending on policy.
human driver was not negligent and causes a fatal car accident.
Human does not get criminal charged. Insurance pays out depending on policy
AI driver causes a fatal accident.
Nobody gets criminal charges. Insurance pays out depending on policy.
You claim that you would rather have 20,000 people die every year because of "accountability".
Tell me, what is the functional difference for a family member of a fatal car accident victim in those 3 above scenarios? The only difference is under 1) there would be someone receiving criminal charges.
They recieve the same amount of insurance money. 2) already happens right now. You don't mention that in the lack of accountability.
You claim that being able to pin some accidents (remember, some qualify under 2) on an individual is worth 20,000 lives a year.
Anybody who has ever lost someone in a car accident would rather have their family member back instead.