Earlier quoted context omitted.
Thank you someone for bringing this up. I can't believe how many actual reviews (not just meme's poking fun at iOS6 maps) have missed this crucial point. This isn't about Apple trying to somehow hurt Google by rolling its own maps app, this is about Google not giving Apple full access to their maps.
The issue is nobody knows the truth here. I think the more plausible scenario is that Google wanted something that Apple refused to give (e.g., advertising revenue, user data, etc), making it not so clear cut as "It's XX's fault!"
In recent weeks, I've seen the further claim Google was willing to license turn by turn but insisting on user location data for Latitude.