culture difference

The most impressive thing I first noticed in the states are the friendliness of the people. Everybody just had a smile on their face and say "Hi" or "How are you?" to each other. It was very strange but it made me feel very good too. I felt like people care more about each other. Nobody ever greet each other in my country. If you try to say "Hi" to someone, you better watch out or something might happen to you.
But after one semester in the states, I figure out "Hi" or "How are you?" are just ways of greeting each other in the United States. Nobody really cares about the answer to the question. That was pretty strange...