I think that most people arent, its only an observation, when I think that someone is not interested or making small talk I think I would give a salutory reply which would amount to "fine" or "okay" in the manner you mention there. Most of the time when people ask how people are doing they are not really interested.
Meeting people who either genuinely enquire as to others or give genuine responses is generally interesting and can make for some really misjudged situations, I've seen people casually ask in the salutory fashion only to become frustrated if they get a proper, indepth response and the converse is true too.
Its a little like the joke in one of the Terry Pratchett books about someone asking one of the disc world's leading philosopher's at a party "why are you here?" and the philosopher took eight years to answer, the humour is contained the misunderstanding, the enquiry could be a serious philosophical and existential question, as the philosopher interpretted it, or it could be more simple, the consideration of which it is could be a source of musing all by itself.