As an American, I view it as an option to start a light conversation. You can decline the option with a simple "Good, thanks", or you can genuinely answer with a light comment and see if the other person reciprocates. Answering with a particularly serious topic will likely catch the other person off guard, so people avoid that, but to say Americans don't actually mean it when they ask how are you misses some of the nuance of the situation.
There are important contextual and regional difference that apply too. You're more likely to get a genuine reply in a place like the rural Midwest than you are in NYC. You also are more likely to get a genuine reply from a person relaxing at a bar than the cashier at a fast food drive through window. There are many people who will take the question as an invitation to talk if the situation is right.
There are important contextual and regional difference that apply too. You're more likely to get a genuine reply in a place like the rural Midwest than you are in NYC. You also are more likely to get a genuine reply from a person relaxing at a bar than the cashier at a fast food drive through window. There are many people who will take the question as an invitation to talk if the situation is right.