That is the norm. I think it has something to do with children being formed from increased contact with the people who love them, their parents. Even the best intentioned professional teachers cannot possibly devote the attention and certainly not the love that children need.
Also, a group of children will descend to the lowest common denominator as far as behavior goes. If they spend most of their time with their peers, this becomes their character.
It's a sacrifice to home-school, but it's an investment that will pay off many times over in educational results, character building, love, happy times, normal marriages, wonderful grandchildren. My best investment was in home-schooling. It has made me a happiness-millionaire.