This is one of the most sickening, heartless things I have ever seen. It's not as much the fact that she got hit by a car, because people do everyday. It's the fact that people didn't even look at her or acknowledge that she was hurt. I may not have the same mentality as any of these Chinese people but when someone is hurt or injured (especially a child) you help them. I don't give a bonk what country you are from, what religion you are, or what race you are: it's human nature.
That's wrong actually, you're living in a utopy.
Cases just like this one and some even worse happen around the world and people don't care, like, for example, vagabonds. People walk by this people and don't even look at them, even though they know that they have no home, no family, no money, no food or water, so why don't they stop and help them? Even one dollar would be a fortune in a beggar's eyes, he could eat for a day with it, so why not give them one buck even though it's very little for you? Because hey, it's a dollar! You can buy ice-cream with it!
Human nature is selfish, people know that in Somalia there are hundreds of people dying everyday because they have no acces to drinking water, and what do we do? We say "hell with it", scratch our balls, and move on. I know it's different when someone is dying right in front of your eyes, but like someone else said, the kid was pretty much dead already, and you would have to pay all the medical bills or even go to jail if you tried to help, so why not look away and pretend it didn't happen? I wouldn't, and probably you wouldn't, but most people would, and it's not a problem with chinese "culture" either.
On-Topic: In a newsletter I read that they actually talked with the first guy that ran over the girl, and he said something like "If she had died, it would've been sufficient with a compensation of 20.000 yuan (like $2500) but if I took her to a hospital, it would've been hundreds of thousands of yuan". That's still no justification, but it explains why no one helped her or called an ambulance.