This is a result of U.S. law being based on compromise. The legislature, especially in places like Utah, has been reluctant to stand up against the old "spare the rod, spoil the child" mentality. Instead, we count on people knowing how to beat their kids discreetly.
If these poor children had been girls instead of boys, I wonder if the police would have been a little more sympathetic to the harm being done.
"it's good to be young but let's not kid ourselves -- it's better to pass on through those years and come out the other side with our hearts still beating;
having stared down demons and come back breathing." -- John Darnielle