I might argue that the situation is in part a matter of "like attracts like". I've you're going to get executive types to contribute and to encourage/force their workforces to contribute, you have to present them with an "executive" type interface. (If it walks like a duck and talks like a duck... and plays golf like a duck...)
My thoughts next turn to "hypocrisy". These are supposedly charity endeavors. But much of their activity -- fundraising activity, at least -- is just more status seeking and building and fraternizing.
There, for me, lies the heart of the matter. When in the minds and/or actions of the top level participants, charity work is anything but.
(I'm "on the outside" looking in, and perhaps I'm too cynical. I want to believe that people have more depth than this, and some individual acquaintances who travel in those circles sure seem to. But it makes me wonder.)
No wonder they are not more effective.
I'm not entirely comfortable with my comment, but I'll make it for the sake of the point about "like attracts like".