This is a horrible analogy. You would never be able to go into a store, buy a CD, and ask them for a couple of other copies for your brother and father who live in the same house as you. But you can with Apple Music. So there's your analogy out the window right there. It simply doesn't work because, as someone else pointed out, CDs are antiquated technology that has been superseded. It was a completely different business model back then, where you had one physical copy. With streaming, this whole one copy thing doesn't really work. You have a copy on all your devices already, which you couldn't have gotten with CDs (you can't go in, and be like: well I have a walkman, a home stereo, and a car stereo, can I get 3 copies of this for the price of 1?) As much as you may want to find an analogy there, there's already too many differences in the business model for it to work.
FWIW, I agree with everyone else, the concept of Family Sharing is very limited in scope, and it really annoys me that they bundled some of the really cool iCloud family stuff (shared calendar, photo stream, location) with the iTunes family stuff, so it has to be one credit card even though I'm financially independent from my parents.