People bumping into you don't say excuse me in Norway, and many other countries ... the opposite is in the US:
If you approach someone in a hallway, they will say 'excuse me' just because you are on 'collision course', or if you are blocking the hallway (or some other confined are) talking to someone, when a stranger pass between the two of you, he has to say 'excuse me'.
About saying hallo etc. You call up a hotel, travel agency or airline in the US: 'Hello and welcome to American Airlines, hope you are having a nice day, this is Amanda Anaconda, how may I serve you today, sir' ? All this 'fake' politeness tends to be hit by inflation !
Also, 'How do you do ?' is seldom answered other by the same quesion, or answer with routine.
Scandinavians in general are not as open in public places, but on the other hand, Americans are not generally easy to make close friends with if you haven't known them for a long time.
And all this is generalizations !