I'm listening to music on Google Play Music All Access (whew!) and I thought I'd share the album. Seems easy enough via desktop browser UI, but there's a problem. My Google Play account is a "family" account I set up so app and music libraries can be synced among all of the family devices. My All Access subscription uses that account.
The family account doesn't have a Google+ profile because both my wife and I have individual accounts and sharing seems to me to be a more "personal" activity. I share a lot (perhaps too much) and she shares very little and in a more targeted way.
I'm not sure if I switch accounts to my personal profile if I'll interrupt my music listening since I don't have the same access the family account does.
I also don't know what the intent regarding paid services is. Would Google prefer that I pay twice for everything? (I'm sure they would!) I assume that what I'm doing is in line with the terms of service. If not, that's a completely different problem.
None of this even takes into account other Google Apps accounts I have.
I had the same problem with Apple accounts and while Google makes it easier to switch on the fly, it seems that something else needs to be done. A way to break out people and services in a way that makes sense both socially and commercially.