Where the accident took place was a no-fault state. There are variants of no-fault, in most states the laws are written so the lawyers can still make their money.
This was one of those cases where the only way to get to the solution was to put it into a courtroom, I think. It's ugly any way you look at it, except for the blessing that there were no serious injuries. You can replace any airplane in the world in half an hour with Trade-a-Plane.
The airport is clearly not safe, and it wouldn't be safe even if there wasn't so much vegetation blocking the view both ways. But the owner of such a field can say, "well, I always come in steeper than that in my Helio" or whatever... it was a bad conglomeration of events. If the kid had been driving a pick-up truck instead, he'd just have seen a shadow flash over him and wondered, "WTF was that?" Dick wouldn't even have seen the car pass under him (where's your attention on short final?).
I would suppose that the no-fault statute in the case at hand prevents either party from suing the airport owner. Dick and Karol would also have to overcome the legal doctrine of assumption of risk -- they presumably knew they were going in to a less than ideal field. But in a no-fault state, the insurer just pays claims and doesn't quibble about fault.
For those of you who only fly gyros, a C150 with its forty degrees of flaps comes in pretty steep for a fixed wing trainer, especially if you are trying to nail a short field landing, but not like a gyro.