Where I grew up, we don't really say "hello" to everyone in a public setting. At work, yes, because you want to be seen as polite, but probably not to people you don't directly work with, at definitely not at the post office. Since to greet is to be polite in Austria as well as in France, I've gotten a few funny looks this summer when I've had errands to run--the workers stocking at Big Lots probably appreciated a little kindness, at least! This also meant that I was prepared already when I came to France.
In Green Bay, it's decidedly small town to say "hello" to complete strangers, unless you have a point to make, or a question. Then, you get their attention, say your peace, and leave them alone. If you don't, others might take it as a sign that you've just escaped from the funny farm... You just don't say "hello" for the sake of saying it. But, if you don't say "bonjour" in France, it's considered rude.
A couple of days ago, I caught myself doing that--falling into the French way of thinking--at the laundromat. I don't have a washing machine, and normally I go every two weeks (when I run out of underwear). It's expensive, but so is everything else in France. I recently discovered mold in my apartment, so I hauled more than normal--pain in the ass--but I do not want to find mold in scary places like my bed...
Story: I'm waiting for my load to finish, and these three girls in their early 20s come in. They had taken up all of the 5 euro 30 minute washers (I had to shove my stuff in one of the mega-load 18kg 10 euro washers) and then--then!--they didn't even say "bonjour" to me!
I immediately thought, "Gee, those girls are rude!" And then they started talking to each other. In English. As far as being able to place their origins, I'd say from their accents they were from New Zealand, but I'm no expert. They were definitely rude by French standards, but I can forgive. They might not have been rude by New Zealand standards.
I wonder what else about my perception has changed from living abroad. Am I becoming more French as the months go by? Hard to tell.