I smile all the time because I'm a happy person. If I hear laughter, I'll just smile cuz I'm happy someone else is happy. I can't help it. If someone gives me a big smile and a hello I'll return the gesture with sencerity
Why was this downvoted? It actually happens. I'm not saying it's just America, but there's a lot of pressure to be a good, happy, healthy and always springy person. My own mother has considered going down that path because of all the stress.
Happiness is strongly encouraged to Americans even to the degree of pretending to be happy. That's why we always say "fine" when people ask how we are.
If you're a stranger taking about lying strangers on the internet, does that not make you a liar?