Thanks for clarifying about their mapping sources. I assume they must do something similar in other countries.
As for why Apple would benefit, I'm afraid I don't agree. Sure, having a few dozen more employees with deep mapping experience would probably be great, but I'm not sure it's the real issue. Nor do I think it likely that the user-provided data would trump the quality of any of the major map players at this point.
If you look at the complaints that people are making, many of them down to public transit, poor proper name matching, and regional map quality. Of those, I doubt Waze will provide any meaningful improvement for Apple. To my knowledge, they don't touch public transit, because that's counter to their target. I seriously doubt they do well with proper name searches (do they even support it?) because their target is the commuter, not the guy looking for the nearest Chipotle. And for regional quality, I'd bet that they're weakest in the same areas that Apple is weak in.
I'm not sure why you think mapping data from Nokia or TomTom would be updated on a yearly schedule. The fact that non-connected GPS devices might be updated on that schedule doesn't mean that their databases are updated on that schedule, or that partners would be limited to updates on that schedule. Nokia and TomTom can, and almost certainly do, update their data constantly, just like Google Maps, and Waze, and undoubtedly Apple as well.