Earlier quoted context omitted.
Unless you have some source, I think the "developing countries especially" affirmation is unfounded. This happens too frequently in all countries, developed or not.
If you are right, that makes my point even stronger, doesn't it? Do you think I am being downvoted for saying we have a lot of ingroup violence or for suggesting there is more ingroup violence in developing countries? These seem to be uncontroversial points. I live in Nigeria. Children get beaten here. From their media, I know it's the same in other African countries, India, etc. Everyone accepts it and we are proud…
Still, according to page 172 of this report, it seems you're right, because UNICEF puts more effort at developing countries, although their scope covers much more than just domestic violence: https://www.unicef.org/publications/index_74865.html