I, and many others, take the position that there really isn't any practical gradation between more-or-less conventional driving, maybe with light lane switching assistance or something, and full on "Level 5" autonomous driving, because the idea that human brains can watch something for hours at a time only to take instant, sub-second actions every few hours is an insane model of human cognition.

I don't disagree with the idea of having a gradient to measure our progress up to full autonomy, but I haven't seen much to say that we should deploy the intermediate stages. Until autonomy can be reasonably guaranteed at at least human levels of safety under the assumption of no human control, it really shouldn't be deployed. "But the human had 673 milliseconds to take control and avert the accident! It's their fault!" is simply not a reasonable defense.