Earlier quoted context omitted.
Who knows what's going on behind the scenes? Example: Last time I read /r/funny for a period I noticed a wave of "look at what funny thing I did with these Coke bottles" posts that were so obviously part of a marketing campaign that surely reddit admins noticed it too. I don't think they would allow that if they weren't in on it. In that case they may have even helped with the upvotes so no external service where you…
There's actually a good incentive for moderators to be in on this, as they aren't paid by reddit for their (in sometimes massive) unpaid labour. If a marketing company comes along and says, 'hey, you've done this so long, don't you think you should deserve some money? just let us run our campaign on your subreddit and we'll pay you!' quite a few moderators would agree. Admins might not notice.
They might not have noticed a few isolated cases, but they sure would have noticed the phenomenon as such by now. The company would have an even bigger incentive now to try to get such monetization for themselves instead of letting others make the money with their site.