I don't know the ins and outs of it, but I suspect neither do you.
Maybe its a payment plan they work out. Or any number of things. You say its a reward, but perhaps We don't have the luxury of giving out 'rewards' to kids? As long as the best kids are still there, I have no problem with it. I also do accept that it isn't exactly ideal, but that's life, you have to prioritise your allocation of scarce resources.