Poor braking/steering, lack of skid control, improper use of eyes, and poor off-road recovery.
What Are The 4 Primary Causes Of Crashes?
I would guess tailgating. Those others reduce reaction time but in most cases the driver at fault was already to close to begin with.
More than likely people ate on the phone talking, listening to the radio, have their music jamming high, or a friend is in the car and they are looking and talking to them