I've witnessed a few incidents like that. One was in Morrisons when this car drove straight into a parking slot and hit this car duff. The owners two little girls were sat in there at the time and the old boy who had hit them asked where their parents were. On being told they were in the store he sent the girls to go and fetch them. I stayed where I was to see what happened and as soon as they were out of sight he reversed out fast and sped away with the drivers door flying open. He was obviously drunk by his body language and as he left through the exit the girls mother ran over. As it turned out it was someone my wife knew. I gave her his registration and she phoned the police. Unfortunately he didn't get breathalysed because the police didn't bother going to his house until the following day.
Another instance was a street in town and a woman reversed into a space like a demented loon and again hit a car duff. She immediately drove off, knowing full well what she had done. I saw her park up further down the road and get out. As she did so she inspected the damage on her car then went off on her errands. The owner of the car that she hit hadn't come back by the time I left so I put a note under her wipers with my phone number. When she rang I told her I would act as witness and I gave her the car registration.
Best one was when I was pulling out of a road junction. I stopped because a car came over the brow of a hill and then thump. Someone had run into the back of me. Again we knew the female and she started crying and was very apologetic. She said she shouldn't have been driving because she was worrying about her mum who was in hospital. I told her to forget it because I had my car booked into an auction the following day and there was already a dent in the rear from another incident of someone who cannot park. That was it, or so I thought. Later that night I had a call from her insurance company saying that she had told them I had reversed into her
The moral of the story is don't trust anyone and in instances like that do not feel sorry for them. The insurance company didn't persue it but I would have had a job to prove it was her driving into me.
Sorry about the long ramble but life is full of surprises, even coming from those you least expect it to