How can he cite me for a "speed/style" citation if he didn't see the accident?

I had a car accident involving a parked car (during winter). I turned into the smaller car with my pickup at a low speed while parking. It destroyed the plastic bumper of the smaller car. I called the police and when he arrived he remarked on how much damage the plastic bumper had. He cited me for "care required". I wasn't speeding, I was parking and he did not witness the accident.