One thing that many people do is drive while eating. Most people don't think that eating while driving is dangerous, and the majority of people who do it have done so for so long that it is commonplace.
Biologically speaking, our human bodies are still very poorly equipped to survive serious body trauma. Unfortunately for many drivers and passengers, car accidents are much more violent experiences than they may realize at the moment. Even when modern safety features are present in a vehicle and the passengers are using them correctly, serious injury is possible in nearly any kind of car accident.