Because other weighting factors suggested they should be shown.
I wasn't implying a simplistic 'everyone knows where X is, don't show it' system - just that being well known could counter-intuitively reduce the need to show a label at some zoom levels.
You're seriously going to argue that NYC isn't immensely important?
From Wikipedia:
"New York is the most populous city in the United States, and the center of the New York metropolitan area, which is one of the most populous urban areas in the world. A leading global city, New York exerts a powerful influence over global commerce, finance, media, culture, art, fashion, research, education, and entertainment. As host of the United Nations Headquarters, it is also an important center for international affairs."
When the aliens came to Earth in "Independence Day", they didn't blow up Philadelphia... they blew up New York.
Except for that there are no landmarks shown on any of the examples. Looking at the maps, nothing is changing except for the cities and the placement of the highway labels.
The adding and switching of the different cities does seem completely arbitrary.
