Because their parents are a) lazy, b) trashy, or c) their daughter's "best friend."
It's really sad too that parents do that, kind of living through their children. It so hurts the child for the future, imo.
My brother and sister-in-law do that with my 4 year old neice. They aren't involved in the church and it shows. We pray for them all the time. Although my brother was raised believing in God and going to church and all that, he has fallen away because it's just not important to him and his wife doesn't know much and seems cut off from wanting to know.
Meanwhile, their kids will suffer as they don't guide them with God's will, imo. And I can already see my sister-in-law is forming a "best friend" type thing with my neice, with what she subjects her to (TV programming for teens (not little kids), the clothes she wears, verbage she uses, etc.). What ever happened to kids being kids? Why do they have to grow up so damn fast?
As parents, we're responsible for the future of our country, and our children are that future.