it doesn't... sorry, grffindoor, but the park/the ride operators are responsible for this one, and if they're sued they have only themselves to blame. Unless they can somehow show the little girl sawed through the plank or something.
It says suitable for children of 6+, but children differ in height, maturity and ability to deal with things. Just under 1m is the average height of a four year old so 1.1 m is not far out. I cannot see that you can blame the parents without any facts. The fact is there was a hole in the walkway. Parents cannot be looking where there children are walking all the time.
if this child didnt fall...then it would have been someone else.
you cannot blame the parents for shoddy woodwork.
saying she shouldnt have been there is nonsense - it could just as easily have been the queue for a childs ride or any other queue...
what parent is going to say "oooh we best not queue for a ride...its too dangerous, the fence might break" that woul dbe ridiculously paranoid...