It's a point of clarification that the originally listed study doesn't take into account, but which could be important to the broader discussion. Especially considering that while this vehicle had LIDAR, the other autonomous vehicle fatality case did not.
> as are basically all other prototype fully-autonomous vehicles
As I pointed out with examples above, no, they are not.
You can get depth sensing (time of flight) 2D camera Orbecc Astra for $150 or 1D laser scanner RPLIDAR for $300. Of course they are probably not suited for automotive, but for me even extra $2000 for self-driving car sensors isn't that much.
LIDAR is also not perfect when the road is covered in 5 inches of snow and you can't tell where the lanes are. Or at predicting a driver that's going to swerve into your lane because they spilled coffee on their lap or had a stroke.
With erratic input, you will get erratic output. Even the best ML vision algorithm will sometimes produce shit output, which will become input to the actual driving algorithm.
Neither are humans, and a self-driving car can react much faster than any human ever could.
Instead, LIDAR should exactly identify potential obstacles to the self-driving car on the road. The extent to which machine learning is used is to classify whether each obstacle is a pedestrian, bicyclist, another car, or something else. By doing so, the self-driving car can improve its ability to plan, e.g., if it predicts that an obstacle is a pedestrian, it can plan for the event that the pedestrian is considering crossing the road, and can reduce speed accordingly.
However, the only purpose of this reliance on the machine learning classification should be to improve the comfort of the drive (e.g., avoid abrupt braking). I believe we can reasonably expect that within reason, the self-driving car nevertheless maintains an absolute safety guarantee (i.e., it doesn't run into an obstacle). I say "within reason", because of course if a person jumps in front of a fast moving car, there is no way the car can react. I think it is highly unlikely that this is what happened in the accident -- pedestrians typically exercise reasonable precautions when causing the road.
[1] https://www.cs.cmu.edu/~zkolter/pubs/levinson-iv2011.pdf