I think you have to look at this from a certain perspective. Think about it, this is a country of 1.3 billion people. How often does this actually happen?

Secondly, think about incentives. Maybe I am hopelessly naive, but I believe that the majority of human beings have something built into them that stops them from hurting others. For the majority of humanity, you don't need laws against murder, internal morality and social pressure is sufficient. However, this is a small subset of humanity that would make RATIONAL rather than MORAL choices about murder if forced to make a choice about it. This is the reason that murder has such high penalties, for those people.

tldr; China needs to raise the expected penalty for engaging in this sort of behavior to the point that it is not rational. This isn't necessary for the great majority of Chinese (any more than it is anywhere else in the world) but it is necessary for some.