I make the effort to talk to the other party after any contact. The two most blatant 'hits' that I have taken (sideswiped in the middle of a straight in qualifying when one car pulled out to pass another, sideswiped several times along the entire side of my car on turn 3 of a race - both times by cars not racing in my class, but in a class where too many drivers seem to think that everyone is racing them...), I never heard a word from the offenders. In both cases I know they spoke to the Black Flag Steward, and at least in the case of the latter - that happening in the race served as some form of penalty. I have not yet ever considered writing paper for driving, but if the situation warranted it, I certainly would.
I have had one significant incident in class that really was just racing. We were lapping cars late in the race, that were also lapping an even slower car, and all came together at the slowest corner on the track. I got a lane on the inside, and took it, he didn't think I could get there and turned in, our front wheels hit, he got turned pretty far - made a great save as I backed out of it hard, but still ended up with a fair amount of bumper to side impact and a messed up alignment - he also went on to beat me.... The other driver was pretty hot afterwards, because he thought his car was severely injured mechanically. We still made a point to talk about it, and are still good racing friends who will race each other very hard.
In my last race, I accidentally touched the car in front of me bumper to bumper in the final turn. Neither one of us could feel anything, but he went around, and I am sure I loosened him up. He was not in my class. I asked my crew to go find him while we sat in impound, tell him that I was sorry and that I would be coming by to appologize in person. I wanted him to know as soon as possible that it was an accident on my part, and in hind sight a dumb move to try and get a 'perfect draft' off the last turn in a race that neither one of us had an in class competitor near us.