From reading people's experiences on here, some clearly do take them seriously, because some are getting the support they need. I am unsure why some may get it and some don't; but I think this may vary in answers in itself. Sometimes we may never get to finding an answer.
Yes, I think the 'how are you?' question, is a kind of a greeting, rather than an actual question that they want you to answer. I've always taken it as a greeting, so I just say yes I'm fine, even though I might not be.
I'm sorry you feel that you are in need to ask this question. I hope things improve for you.