I'll agree with you that "watch your kids 24/7" is unfeasible. But I did think of something that would get the same results in this case: teach your kids to respect the property of others. It always confused me that, for example, trampoline owners could get in trouble because local children, without the permission of the owner, came over to jump on it and fell off and broke a bone. The kids are at fault, and that reflects on their parents.