They bought Waze "mostly" for the userbase, but the fact that they have some of the best traffic data is useful too.

. . . and is interesting as it's almost completely orthogonal to this.

Google's existing offerings fail most spectacularly for knowledgeable people in urban environments (I cannot overstate how much GM's handling of subways drives me insane), which is the niche this lot have successfully found. Apple seem to have a lot of customers in that bracket so they are the better fit.