I have a suspicion that the "volunteer-mods" on the big Reddits, like the Wikipedia admins, are infiltrated by people paid by interested parties to represent their interests on those popular web sites. In the case of Wikipedia, I recall a story about how one of their admins was a woman in Canada who was a former British intelligence agent with whatever the British equivalent of the CIA is called. If governments and NGOs can infiltrate Wikipedia to do things that are specifically against its rules, they can infiltrate Reddit and probably have.

Most people are too busy to have the time to be an online moderator and those who have the time typically don't have the political skills to get appointed as a moderator of a large online community. That's why the best way to hire a good mod for your online community is to make it a paid position and to randomly monitor them for evidence of bias and/or abuse of power.