Had the child been killed, it is fairly obvious that the zoo would have to pay out, but does that mean the parent had no duty to supervise? Of course not--all parents have a duty to ensure the kids' safety.
We think this person we saw online, expressed it best:
"Let me get this straight... if you turn your back on your child in a zoo, who tells you he wants to go into a gorilla cage, and he goes in, causing the gorilla to be put down there is no negligence...but parents all over the country are being charged for negligence for allowing their kids to play
a. willfully inflicted unjustifiable physical pain or mental suffering on a child,
b. willfully caused or permitted a child to suffer unjustifiable physical pain or mental suffering,
c. caused or permitted a child in your care or custody to be injured, or
d. caused or permitted a child in your custody to be placed in a dangerous situation;