I see this as a trend that the driver is normally not charged if he stays at the scene and victims are either pedestrians or cyclists.
The only time drivers are charged are
1) hit-and-run;
2) DUI or suspended or no licence;
3) already wanted by the police;
4) the victim is in a car or motor vehicle.
In the case of this story, it's hit-and-run, DUI and no licence.