>A human driver could have seen the person and/or bike from a long way off.
Not true at all, the person was not standing under lit streetlights and was in the shadows. Humans have problems detecting objects in the shadows, especially at night.
3M made a video illustrating how difficult it is to see people at night. In this video, people wearing bright-colored clothing don't even show up until 250 feet away. According to the national safety council, a human driver traveling at 30mph at night, may take up 500 feet to react to and stop when there is an object in the road.
I reccomend watching this video as it strongly changed my views about night driving.