Before moving to the USA, my wife and I took a house hunting trip. During this trip, we staid at a hotel. The first days after moving here we also staid in a hotel before actually moving into our apartment.
What surprised me during our stays at the hotels was the fact that in the elevator, on the hall-ways everyone was saying hello and wishing us a good day.
At first I perceived this as annoying, particularly because Americans say hello by asking "How are you?". This apparent question, is in fact a form of greeting and nobody expects and answer; in fact nobody wants a honest answer.
After several "How are you"s and "Have a good one" (meaning have a good day), I believed that this is the social norm around here. From a certain point of view, it's kind of nice since it gives an impression of living in a polite society.
After we moved to our apartment which is in a relatively high building (14 floors) equipped with 4 elevators, things went differently. We were the weird people who said “Hello” and “Good bye” or “have a nice day”.
Apparently, the social norm in the building(s) where we live is to completely ignore other people, even if you come across them on the hallway (people who live one or two doors away from you) or in the elevator.
In the Netherlands there was a joke that you live in the most densely populated country in Europe and you don’t know your neighbors. That was partly true, but here things are even worse. Here if you say hello or hold the door for someone, you’re the weird one.