Well everything has pretty much been said, but speaking as a person that has been hit/damaged in parking lots 3 times and never had anyone own up to it, to date I have a big dent/scratch on my roof (who knows how they managed that one, but I think some put something heavy on it while they unlocked their vehicle and then dragged it off), A gouge in my passenger door from another persons door and some one backed into my rear end breaking my taillight and scratching/denting my trunk and bumper. Funny thing is I make a point of parking in wide spot and out of the way, I'd rather walk the extra 100 feet... but I don't know what it is about some city folk, I come out and even though there are 20 empty spaces around me some one will have parked right tight next to me... like they were worried their vehicle would get lonely...
Anyway I'm getting off track as it is a subject that I have issues with

... but speaking from someone that has had thousands of dollars damage done to his car without anyone claiming responsibility I think what you did was rare, upstanding and speaks volumes towards your integrity as a human being.
(Besides if I heard or saw my neighbor mowing his lawn and then saw my broken window a few hours later I'd put 2 and 2 together and come knocking)