I wouldn't want to commit to an answer right now, but the Hansonian Hypothesis does make the right prediction in this case. If I'm directly helping, it's very clear that I have altruistic motives. But if I'm doing something much more indirect, then my motives become less clear. (E.g. if I go into finance in order to donate, I no longer look so different from people who go into finance in order to make money for themselves). So you could take the absence of meta-charity as evidence in favour of the Hansonian Hypothesis.