Wonderful observation Guido!!
Ever wonder which country tops the happiness survey. It's Nigeria.
http://news.bbc.co.uk/1/hi/world/africa/3157570.stm. May be the same reason why you do not see many people with smiling faces in the west.
I was born and brought up in India. I was in the US for about 4 years. US is the only western country I have had a chance to live in. So I cannot comment on the other countries. What I felt was the expectation from life was pretty high in the US. Happiness is also about meeting expectations, in my opinion.
One day I walked into office(in dallas), to see my co-workers grumble about labourers trying to fix the road during office hours. That got them delayed to work by 15 mins. Everyone was delayed that day and I was thinking, they should be happy the government is taking care to fix a broken road. I could not understand what the complain was, initially..