Corruption in most of these countries is a negotiation game that is conducted implicitly. That's why playing dumb is so effective--if you don't know the rules of the game, you can't play, especially if you don't share a language. So, for every time where someone has forcefully pressed the point and made it clear to you that a bribe was expected, there have likely been a hundred times where a native in your place would have been expected to pay a small bribe of some sort.