I am astonished, when I pause to think about it, to discover myself to be an author of humorous novels for children. Or an author at all. I had a childhood much like everyone else's. What went wrong?
As an adult, I'll give a writer 50 pages. If the book doesn't interest me in 50 pages, I'll say the heck with it - there are just too many other things to read. A child won't give you 50 pages.
Adult novels are as ephemeral as newspapers. Children's books stay in print for decades.