To me, it seems fair to share revenue according to population size. Sure, some counties are worse of than others, but I don't believe Kenya has reached that point where affirmative action is required to straighten out regional differences. People are struggling everywhere. What would make it even fairer is if the counties get a bigger share of the pie than the central government.
Economic output should be the primary criteria for redistributing funds not population size of county. Perverse incentives should be avoided. Otherwise we will have population explosion. If GEMA and RV contribute more to the national kitty per capita no one should begrudge them.
There is really not much anyone can do about corruption if a significant portion of the population no longer buys into the system. We can see that right here in the US under Trump.
Assuming you are saying GEMA and RV should get more or less resources, there has to be mechanism to determine that. I don't believe there is one in place. So population makes sense in the meantime. Still, even in a Federal system like the US, some states(mostly Blue) are net losers subsidizing others like (Kentucky) to enjoy living standards that their own contributions cannot sustain.