Maybe because parents like to have control of their children's religious upbringing and don't expect well-meaning strangers to try to change their kids' faith through an anonymous charity program.
Yes that is why in today's society we have children with no manners are rude to adults have no respect for thier parents, children that have to go to school with metal detectors because school is no longer safe from violence,
drugs, pedophiles teenage pregnancy.
Parents are sure doing great these days teaching kids about religion.