It's interesting that you brought this up, when we sat down to write this, we didn't feel there was actually good terminology yet to refer to this space. We chose 'ride-sharing' as the least-bad way to refer to the industry after informally surveying what journalists had been using so far, for consistency. At least for Lyft, Sidecar, and UberX, the 'sharing' part makes some sense to me because you're sharing another person's vehicle that they possibly already owned, while for Uber Black and Lyft Plus, these are professional services so the term is less appropriate. I would definitely welcome a new term to describe the rides space.

Whilst "unlicensed taxi" is probably too perjorative (although more accurate I feel) I would go with something like "Alternative Taxi"?

I suspect that it won't be many years before it's just plain "taxi" again. If Uber and other alternatives are proving the current companies are over charging they will just succeed in becoming licensed in a world of lower charges.

Exactly. Long before Uber there was an idea of digitizing carpooling that went something like this:

http://www.youtube.com/watch?v=CTn-ev4fjsM

Even then, it's not technically sharing as you are getting paid but the idea was that you are getting money for very minimal effort and in return providing good cheap travel options for people. Not just another taxi service.

because you're sharing your 'ride' (def. 1) http://www.urbandictionary.com/define.php?term=ride