If there's hardly any individual desire, as you say, to fund the development of the poor then taxes in that pursuit are illegitimate under a theory taxation happens by the assent of the people (even if only roughly a majority or their representatives).
Given that most taxation done with the the advertised goal of helping the poor in Australia does happen with popular assent of individuals, I would theorize your position is false and that people do have some individual incentives to develop services offered to the poor -- for profit, humanitarian / charitable reasons, and a variety of other considerations.
Given that most taxation done with the the advertised goal of helping the poor in Australia does happen with popular assent of individuals, I would theorize your position is false and that people do have some individual incentives to develop services offered to the poor -- for profit, humanitarian / charitable reasons, and a variety of other considerations.