Apple tried to be smart and sourced base maps from different vendor in different regions like TOMTOM... They also sourced geographical data from yelp... Using this multi-source maps/data they tried to develop their own algorithm for routing/360 degree rotation/3D.
They never realized they cannot simply develop an algorithm using base maps, and companies like Google/NAVTEQ/TomTom/Nokia layer additional data points for their algorithm to work.
You will notice this if you toggle 3D on Apple maps or if you try to rotate the map a little.
So collection and layering of data on top of base map is labor intensive, there is no automated way to do this. Google has a team in India who does just this.
Also end result of a map or navi function is visual, some has to manually verify, and when it doesn't work the way it supposed to, they tweak data layer and algorithm if required.
So how ever smart Apple's designers and programmers are, without laborious manual testing results will be odd.
Good thing that Apple bought a 3d mapping company then.