...the obvious interpretation of this is that when Apple built the iPhone they licensed Google Maps but with the clause "the iPhone cannot do turn-by-turn"
This is from Google's Maps/Earth API TOS:
10.2 (c) No Navigation, Autonomous Vehicle Control, or Enterprise Applications:
(i) real time navigation or route guidance, including but not limited to turn-by-turn route guidance that is synchronized to the position of a user's sensor-enabled device.
A valid point, but it is conceivable that a similar clause would find its way into larger licensing/development agreements. Turn-by-turn could have been some gem thy wanted to hold as Google's one-up on any client built using their own API. Truthfully, it would be dumb of Google to give away everything, and keeping turn-by-turn (or even just a broader navigation scope) is something I can see as the ace in the hole they hold onto regardless.
This is from Google's Maps/Earth API TOS:
10.2 (c) No Navigation, Autonomous Vehicle Control, or Enterprise Applications:
(i) real time navigation or route guidance, including but not limited to turn-by-turn route guidance that is synchronized to the position of a user's sensor-enabled device.
- https://developers.google.com/maps/terms
As far as I know, that clause has always been in the TOS (I looked into the licensing in 2010 and it definitely was in there then).