Whatever length of time it is Apple still did it in a fraction of the time Google has been working on its maps.
Also maybe I live in a weird place (Minneapolis) but I've been using the new maps since WWDC everyday and honestly have no complaints, the turn by turn is quite good as I just used it non stop in New Orleans.
Apple took data from 3rd parties (Yelp, TomTom, and many others) and integrated it all together with their own Maps app.
Google has a lot more features than Apple right now, and a large part of their data is sourced from their own works. Streetview gives them good road data. Local gives them all the data that yelp has (and then some).
Apple's Maps is probably where goole was with maps back in 2007 or 2008.
Are you saying Google doesn't use 3rd party data? Because that would be completely false. Look at the copyright notice in the bottom corner of Google Maps for anywhere outside the US/Canada/UK - around my city the data comes from WhereIs, Sensis, Tele Atlas and GBRMPA as well as Google. Other countries have data from AutoNavi, MapKing, SK M&C, ZENRIN, GISrael, INEGI, and many others.
The logic behind creating an MVP doesn't really make sense when the market for the product isn't competitive.
Apple didn't offer their mapping solution as an option in the App Store to judge interest; they forced anyone who buys new or upgrades for any reason to use it.
That's just a made up timeline. They may have been working on a maps replacement for years.