What sort of object in the road would it have been okay for the car to run into?
That it was a person is irrelevant. Why would anyone tolerate a car that runs into anything? What if that had been a Cow, or a Moose or something?
Cars should not run into anything in the road. Had that been a concrete block, it would have likely wrecked the car.
A car that cannot detect objects in the road (regardless of what they are) should not be on the road.
How do you differentiate actual objects from shadows in a visual recognition system. You have to approach the problem without the built-in knowledge we all have of objects. A computer system processing a light sensor array only sees various colors at each of the sensor locations. There is no inherent image. The actual objects need to be differentiated from artifacts like shadows, glare.
Systems need to not only differentiate actual objects from artifacts, they need to discount objects that it should not stop for. You don't want the car stopping because some leaves fall in front of the car, or a trash bag blows across its path. What if it starts snowing or raining? So yes, there are real objects that are ok to run into. It's determining what is actually present in the path of the car that is a non-trivial task, but ultimately doable.