Well - in case this is a real thread, I have to say I agree with those who say that MaryPoppinsMassiveSack should own up. However, it is clear that she is too selfish to do so. I think that leaving the repair costs for the other driver to bear shows her lack of decency - though I am sure she will come back and tell us what a wonderfully charitable and altruistic person she is, and how unfair it is to judge her on one incident. 
Of course, we aren't judging her on one incident - but on her reaction to it. What I find especially nasty is her referring to the driver of the other car as a snotty cow, when she has done nothing wrong at all - the OP, however.....
I have twice damaged someone else's car in a car park, and both times I found the driver of the other car, and gave them my details, and we paid for the repairs to their cars. It was just the right thing to do. The first time it happened, I was in the gym car park, and scraped the side of another car. I went back I to the gym and got paper and pen to leave a note with my details, but then decided to wait in my car until the driver came back - it was an elderly man, who was lovely to me - I was almost in tears at what I'd done. He even sent me a bouquet after the repairs were done.
MaryPoppins - for me it is about honesty. If I hadn't owned up, I would have felt dishonest, and it would have weighed on my conscience. I think what you did is dishonest, but clearly you have lower standards in this area.
Oh - and of course you won't be complaining if this ever happens to you which would be beautiful karma.