Well, its a bit like the cyclist haters frothing at the mouth about cyclists not having insurance isn't it? Your view is a bit skewed by your two negative experiences. I've never encountered damage to a car caused by children playing. But I see every day children (and adults) having to adjust where they walk and play in order to accommodate the needs of those who choose to drive and park in public places.
As someone mentioned up-thread, such damage would be recoverable through household insurance policies or small claims courts. My view is (but I've never owned a super fancy car, just average family cars) is that cars get dings in them. Usually they're mysterious and you take it on the chin. The mysterious dings seem to usually happen in car parks, and are caused by other car owners who then drive off. Maybe cars should be banned from car parks..... Oh, wait a minute