I'm actually working this out as I go and you are helping.
Well so far, we seem to have a system where people go to work so that they can earn respect, which is useful for acquiring resources. And a person can earn more respect based on how hard they work and the type of work they do. And the amount of additional resources they can acquire correlates to how much respect they have. Thus, there is motivation to accumulate as much respect as one can.
It seems you still have a meritocracy with undesirable work. You have just changed the type of work that is now valuable to society (humanitarian), the form of currency people labor for (respect), and I assume the total wealth (accumulation of respect) one can have.
It should be noted that if one does not find fulfillment in humanitarian work, greed for additional resources will be their motivation for participation in the new humanitarian labor force. And most people probably don't find pumping sewage for the good of society to be all that fulfilling. There might be some joy in knowing they helped, but they're also doing it for the respect so they can get more stuff.
You can't change human nature through economics. As long as humans are involved, you will always have greed and exploitation.