Humans are unable to make moral decisions in a few miliseconds. They would either freeze for a least one second and hit the next car or pedestrian depending on which comes first. If they have more time, they would try to avoid collision with the human and hit the car, because you cannot really see other people in there and you do not know how many persons are in there. Also people in the car are better protected. So the safest thing is hit the car. But beside that people know when approaching an truck trailer and they cannot stop, they should aim for the wheels and not the section in the middle. However, most people are unable to implement that so why should be cars be able to do these things?
You have hit on one of the key reasons why trying to implement human reasoning in an emergency; especially since it's usually a subconscious reaction to avoid hitting the bigger, scarier thing. yo can train people to make calm decisions in an emergency situation but that takes a lot of simulator time and practice; something most drivers sorely lack before getting a license. If you wanted to follow the human reasoning it would simply be "CRAAAP.... AVOID HITTING THE BIG THING...DAMN... A PEDESTRIAN