And here is a snapshot from the car camera a second or two before the crash:
The scene looks dark but a key issue is how dark it actually was for human vision. The issue is that car cams generally are significantly worse in low light than the human eye (e.g., Testing CarCam). Many are commenting on this using the darkness of the video as reference but how dark it really was for the operator is a key issue. Also, the operator appears to be looking down.
The final issue is the car's self-driving system most certainly does not depend on visible light sensors so why did it miss this person?