The only problem is that corruption there is routine so you could wonder where those government fees might wind up.
The fees generated by offering one tag for an endangered rhino kill / trophy can support conservation efforts for all the rest. The question is not whether they are endangered, but rather whether there are a sufficient number that losing one can result in supporting its replacement by protecting or procreating two or more.
Depends where you are whether or not they are 'endangered'. They've been pretty much poached into extinction in places where it is illegal to hunt them. In those places where it is legal to hunt them, the herds are getting big enough for them to be real nuisances and pests to the locals. (Rhinos, like elephants, can be quite destructive to crops) Amazing how that works. Where you allow free enterprise to work, folks have an incentive to good game management. Where you forbid the market, things are destroyed.