distinctly Western phenomenon
The exact phrase is specific to few languages, not universal in the West. The literal translation would work e.g. in Spanish or Serbian, not in French (there the equivalent "(comment) ça va" means "(how) does it go", I am not sure how a Frenchman would interpret "comment es-tu") or Polish ("jak sie masz" = "how do you have yourself", direct "jak jesteś" would be ungrammatical). Each language usually has an arbitrary set of standard questions used for greeting, everything outside the set would likely be heard as genuine curiosity.
Personal experience: I have known that "how are you" and "how do you do" belong to this set for English, but somehow I was unaware of "how are you doing". Last time I visited Britain some activist on the street tried to establish conversation with me using this phrase, which got extremely awkward when I responded by "sorry?" and after he repeated his greeting, I replied "what exactly do you want to know?". He must have thought I was a moron.
In Chinese, "how are you?" ("ni zenmeyang?") is used, but it's relatively recent (most likely a western influence); previously "have you eaten?" ("ni chi fan le ma?") was the standard phrase.
I am not sure how a Frenchman would interpret "comment es-tu"
The perpetrator would be suspected of being Canadian.
I've seen an article on LW about Santa Claus and most people were very keen on not lying to their kids (and I agree). I have a little kid who is generally quite truthful, innocent enough not to lie in most cases. I noticed recently that when someone asks him, "How are you", he usually answers in detail because, well, you asked, didn't you? When I was a teenager I hated people who lied and I tended to ignore these unwritten social rules to the extent I could. I.e. I didn't ask if I didn't want to know and people thought I was rude. So, my question is, should I teach him to lie upon these occasions?
More broadly, I was thinking, why am I committed to being truthful, in general? I guess because I would hate to be lied to myself. This is a kind of magical thinking maybe, or maybe it's a part of the social contract. This sort of lying in fact promotes the social well-being because to answer truthfully creates an unwelcome burden on my interlocutor who asked out of politeness and is not in truth interested. But it still feels wrong to lie. Even more wrong to teach your kid to do so.