At one level, corruption can be seen as a problem of multiple equilibria. When bribes are rare, someone who sees a bribe or bribe offer might reasonably expect to be supported for exposing it, and fear being exposed and punished for going along with it. But when bribes are common, one can expect to be punished more for trying to expose corruption.
At another level, however, many policies can reduce corruption. Bounties paid to any who expose corruption can encourage decentralized policing that central powers can find it hard to suppress. And eliminating government agencies whose social benefit is doubtful or moderate, even without corruption, can eliminate opportunities for corruption. I’m told many places are eliminating drivers licenses, to eliminate corrupt issuing of such licenses.
Since policies can discourage corruption, the deeper question is what makes politicians expect to not be rewarded for supporting such policies. Perhaps the people who benefit from corruption have more political information to know how to vote well, and more influence on other voters. In this case they might in effect have more votes, when votes are weighed by voter information and influence. I find this implausible, however.
Perhaps voters find it plausible that the above anti-corruption policies would work, but also find other ineffective anti-corruption policies similarly plausible. If ordinary voters are fooled by these ineffective policies, but those who benefit from corruption are not fooled, politicians may prefer to adopt such ineffective policies. By the time voters find out the policies didn’t work, the politicians may be long gone.
This raises the question: why do politicians have such short time horizons? Why don’t they expect to win by first implementing corruption-reducing policies, and then waiting for corruption to actually go down, before being rewarded by voters? The puzzle becomes more stark when one notices a usual way world-round to get long term project commitment: hire a multinational firm with a global reputation to protect. Yes, NGOs tend to prefer to hire local organizations to achieve charity aims. But they are often “surprised” to see the money stolen and nothing done. When folks really need something done, they hire long-lived multinational firms.
So the obvious solution to reducing corruption, and promoting good policy more generally, is for big multinationals with reputations to protect to run as candidates in local elections! They’d have a long term view that would make wary of making promises they could not keep. Of course upon hearing this suggestion you immediately know why this can “never be”: nationalism. Even voters of basket-case nations couldn’t stand the “humiliation” of publicly admitting they needed to hire foreigners to do something they couldn’t do for themselves.
And so let us admit that a big root cause of political corruption, and of inefficient policy more generally, is nationalism: the reluctance to hire organizations that seem to do the best worldwide in keeping reputations for effectiveness. Of course people do admit this daily in private, as they choose to use products made and distributed by multinational firms. But alas voting is a far fest of idealism, where the ideal of nationalism has more influence.