I have gotten a couple of good whale votes on charitable posts. I've gotten them ignored by whales too. So I am assuming that they're just not seeing some of the posts. But it may be like you and @thecryptofiend said, that it's a blogging platform and charity isn't really something they want to promote.
Some folks give personally in huge ways too, including goods, finances and massive amounts of time. If so, then perhaps some of them are thinking it would be better if they focused on those things and let Steemit just be for blogging.
OTOH, I don't see how a well done charitable post could not be considered good content. I realize some folks just put up a couple of paragraphs, kinda like I did for this entry. But others make it really clear what they're about and offering amazing insights.
Thanks for entering the discussion. I do hope that something gets going to move some of the Steemit opportunity to helping some of these needy people.