What ComradePhil means is: If poor countries' police are corrupt simply because they're so poorly paid, shouldn't the poor countries' police chiefs be honest, as they're paid more? And yet the police chief probably makes much more bribe money.

As I understand things, highly corrupt countries have a sort of 'bribe pyramid' where the police chief remits a certain amount of bribe revenue to his boss in order to keep his job, who in turn gives a portion to his boss and so on, so the police chief sees a lot of money, but will be replaced if he develops a conscience.