Not this. Having lived in Russia, this is something which is neither good nor bad. It just is. The faces are not sad or grumpy, they are relaxed. Nobody pretends to be happier than they are.
You just got used to smiles everywhere. There is nothing more to it.
At least in Russia, when someone smiles at you, it means something.
When an average American is forcing his smiling just to make my day better it means more to me than a grumpy face of an average Russian, and makes my day better, and I don’t care if he is really happy or not, he made me happy, that’s what I like about American smiles
You just got used to smiles everywhere. There is nothing more to it.
At least in Russia, when someone smiles at you, it means something.