Modelling generosity

If a superficially generous act is done for the purpose of modelling, it is not being done out of generosity at all. There is no realistic chance of an onlooker becoming generous as a result of watching such a charade. If anything of it is passed on at all, it will be the parent’s actual motivation (to tell improving lies to children), not the purported one. What is the point of propagating the idea that generosity is a chore but in front of children one must grit one’s teeth and act out the semblance?