How To Get Google Maps Back On Your iPhone
No, It's Not A Post Office
Here's Apple Maps showing the intersection of Market Street and Springfield Avenue in Newark, N.J. Just as an example of what everyone who lives there already knows, the building on the middle left is mislabeled as a U.S. Post Office. It is, in fact, the "old court house"--a very cool building with a great and famous bronze statue of Lincoln out front.
This is the sort of misinformation in Apple Maps that might compel you to use a more tried-and-true map service such as Google Maps.