Because of the amount of deaths, and car accidents cause by the use of cell phones while driving.
Explanation:
Cellphones are a heavy distraction by itself, it keeps you from doing things like school work, chores, or having a social life. Cellphones in the car means a more heavy distraction because you're doing two things at once and if you are not focusing on the road there is a higher chance of you crashing your car and hurting yourself or someone else.
