I think his behaviour sort of makes sense if you consider how scary it could be for him (bear with me).

He's clearly in the wrong. He knows it. Especially in the court of public opinion; he hit a kid, walking to school. It's broad daylight and it happened at a crosswalk. It's not looking good.

Surely, then, it can't be his fault. Taking responsibility is not an option, it doesn't even cross his mind. If he lashes out, if he berates the person he hit for doing something wrong, maybe he can convince himself it wasn't his fault. Maybe he can convince the girl or the bystanders that it wasn't his fault.

I think this is also why people can be so opposed to bike lanes or other infrastructure that promotes mixed use of roads. When most things are built with only cars in mind, it's easier to blame a pedestrian or cyclist because they seem to be guests in a space for cars.