It's 100% because of abusers parents and guardians who want to deprive their children of a secular upbringing and indoctrinate them into whatever nonsense they believe in, as well as discipline them however they see fit and exploit them for money.
Specifically, Articles 13 and 14 are concerned with the freedom of expression, the freedom to seek out, receive, and impart information, and the freedom of thought, conscience, and religion. Article 17 concerns access to mass media of both national and international origin. Article 19 concerns protecting children from abuse and neglect. Article 24 concerns access to healthcare. Article 28 concerns access to education, and Article 29 further stipulates that education should promote tolerance and respect of other people and cultures. Article 32 protects children from economic exploitation.
In the USA, the land of the free, we can't have any of that! If a parent believes the outside world is evil and wants to keep their kids from reading books that aren't about how God will send them to Hell for speaking out of turn, they have that freedom! If a parent believes that medicine is evil and wants to keep their kid from being vaccinated or put their kid on a raw meat diet or use homeopathy to treat an inflamed appendix, they have that freedom! If a parent wants to teach their kid that white people are the master race and that it is their duty to massacre everyone else, they have that freedom! And if a parent wants to take their kids out of school to work on the farm or get into the acting business, they have that freedom!
Sure, a horrific amount of children might be subject to abuse that will scar them forever and potentially lead to their untimely deaths, but that's just the price we pay for freedom! Freedom for parents to treat their kids like property, that is. The kids don't get any freedom.