I still finding it silly that they are trying to go straight for L5 (which is the only case where you can fully remove the steering wheel).

By the sound of it, they already have an L4 going (can drive itself in 99.99% of the situations, might need user take over in very rare cases).

Why not for now release an initial car with L4, and collect pile and pile of data, which is what they need to get over that last 0.01%.

I attended one of Google's talks on this. The rationale is that humans can't be trusted to take control in a timely manner for that 0.01%. Their internal testing with an L4 system on trained Googlers (who were told to remain alert in the event that action needed to be taken) had instances of testers sleeping, eating, putting on makeup, etc. They concluded that if Googlers with explicit training couldn't behave themselves, then L4 definitely wasn't sufficient for the general public; autonomous driving had to be all or nothing.

Or ... the car could monitor the driver too, and alert them when they lose attention.