Three questions:
1. The article notes that the monetary cost to the driver for accidentally killing someone is much less than the cost for accidentally disabling someone.
For drivers that do not have much wealth, and who are the sole source of income for their family, I can see how [1] they might decide that the harm to their family from having to pay that higher cost might outweigh the harm from killing a stranger. People tend to value their immediate family very much more than they value strangers.
However, it seems a lot of these cases were people driving expensive luxury cars. For people with the incomes or wealth to afford those cars, is the cost difference enough to actually cause serious hardship for them or their family?
2. How does this work when the pedestrian is a foreigner, such as a tourist or a business traveler?
Do drivers know that (1) these people will have their medical bills taken care of by insurance or the national healthcare systems of their home countries, so there is no need to kill them, and (2) it would really piss off their home country, which would cause severe diplomatic pressure on China to seriously punish the driver?
3. Drivers certainly cannot count on always being able to finish off any pedestrian they hit. Why hasn't an insurance market sprung up to deal with the risk of disabling pedestrians?
[1] Note: "I can see how" is not meant to mean "I approve of". It is observational, not judgmental.