But so what? Full autonomy needn't even be a business goal of Waymo. They just want full deployment. Having a system in place which reduces or eliminates many/most of the accident root causes would be worthwhile to install on any vehicle on the road even if it technically had a human driver.

The "goal", such as it is, is to have a technology worth using. It's not to transcribe whichever comic book utopia someone has in mind.