Furthermore, if there are street lights, and you go through an unlit area, you should be able to detect the presence of an obstacle because it will be obscuring the view of the road ahead.

Uber's technology clearly sucks, to the extent that I doubt they are even using Lidar. However, the woman driving the vehicle should be arrested for not being aware. If she had been looking at the road for more than a small fraction of the time she surely would have seen the person on the road.