A large number of pedestrians struck by cars each year (at least in North America), are themselves intoxicated, and not fit to walk along roadways. There are many cases where the driver should not reasonably be at fault for a pedestrians erratic behavior.
There's also the "hit-to-kill" phenomenon in China, where it can be financially devastating to leave a person living with significant injuries, but affordable if you had simply killed them (50K USD vs 1M over a lifetime). In extremely sad circumstances, this has motivated people to hit the victim multiple times.