Why? Google has a huge source of information for traffic analysis, time estimates via Google Maps. The "ETA" on Nav is precise no matter whether I'm in podunk Midwest city or Seattle and I get traffic overlays in both as well.
Why?
Ever tried any of their location based features in europe?
I can't say that I have. Granted, there is a huge amount of territory in the United States that is neither San Francisco or New York. And as much as you or I may not like it, it seems pretty clear that Google primarily targets the United States for new features. (Given the crowd-sourced nature of their traffic data, I would venture to guess that it's partly because of legal issues).
It was fine for me in Amsterdam and London.
I have used my android phone for turn-by-turn navigation, finding transit, restaurants and other POI, translating foreign-language signs, etc. making me a pretty independent world traveler in Tokyo, Hamburg, London, Milan, and Paris. I have rarely had any problems with their location-based features.
Pretty much every day for the last two years. My Android phone is my satnav. It works. Faultlessly.
They work for me fine in Melbourne (frequently) and Madrid (though I have used it sparsely there).