Because when the car leaves the road at a high rate of speed THAT IS an accident.
People love to play with statistics, write a headline based on their statistical findings, then push the meme until panic sets in; law makers then step in a pass a new law. Rinse and repeat until election time, then brag about the laws passed.
No, an accident would being hit by an asteroid. Your vehicle losing control and leaving the roadway is not an accident, as the causes of which could be inattention, neglect, DUI, excessive speed for conditions etc. None of these are an “Accident”.