Well, I think people smile for very different reasons depending on the situation. Some smiles are just polite gestures - like when you greet a stranger in Shanghai, it's more about social etiquette than real happiness. But then there are genuine smiles that come from real joy or connection - like when my team at work finally solved a difficult design problem together, our smiles showed real relief and achievement.
Interestingly, I've noticed younger people tend to smile more casually in everyday situations compared to older generations who might reserve smiles for more meaningful moments. That said, both types of smiles serve important purposes - the polite ones keep social interactions smooth, while the authentic ones strengthen our relationships.
Just last week, I saw this difference clearly when an older client visited our office - my younger colleagues smiled automatically when greeting him, while his smile only appeared later when we found common ground discussing design trends.