Why Aren't iTunes Match and Family Sharing Friends?

OK I think I've already found the answer but, I really want to know why. Don't get me wrong, I love Apple products but they do a terrible job at really explaining the proper way of setting up iTunes, iMessage, FaceTime and iCloud accounts. I am constantly helping friends change their settings.

Anyway, we have always had a Match account and had all the families devices logged in under my iTunes account to listen to the music. When Family Sharing came out, I changed things around and have each device set up with individual iCloud and iTunes accounts. My son is able to "ask" for apps that me or the wife approves. I got to looking on my son's phone the other day and noticed that he didn't have any music and it wanted him to sign up for match not turn it on. I logged out of his account and used mine to enable Match. This completely screwed things up. Now he can't ask for apps at all. I'm guessing because the phone thinks it's me. Why won't apple make Match part of the Family Sharing? Makes no sense.