you realized the reason for these things not supported in Google for Work is due to them being new or not work focused

Google for Work has to be stable over features all the items you have listed are pretty new all the family stuff is extremely new and still isn't complete it started with hack into google Music but we are now finally seeing it move into google main accounts as of today you can see it here

https://myaccount.google.com/preferences?utm_source=Google&u...

but you still can't add users from here

Google Fi isn't a for business product is more of an experiment on how to build a better MVNO and also to improve Android i expect in a few years they will sunset it

Google spaces is like two months old.