You're not a parent, are you?
EDIT: neither am I, for the record. But I think a lot of the replies here are a bit too quick to lay the blame on the less tech-savvy parents, who may just be using YouTube in the good faith that an app designed for children will not auto-queue disturbing content (also, the linked article makes a larger point about the "infrastructural violence" of the internet that we should not dismiss to quickly).
https://medium.com/@jamesbridle/something-is-wrong-on-the-in...