It's too difficult. They'd rather have the government tell them what their kids can watch, read, listen to, eat....takes the pressure off of them. Don't want them to hurt themselves by thinking.
The government should not be responsible for our kids, period. The only exception, of course, is in the case of abuse or neglect.
Overweight children will one day grow up and take responsibility for themselves--and they will decide to be fat or not.
I certainly feel sorry for overweight kids---but I don't want that pity to be turned into more government intrusion in our lives.