I am sure no one gets paid to do that. The only service similar to that is the Bounty Police by Royse777. But maybe there is an unofficial bounty you can get from campaign managers if you contact them in private and propose you find rule-breakers if they pay you a bounty for your work. Who knows.

Maybe when PrimeNumber7 said that there is "financial incentive to look for plagiarism", he meant there is the possibility for someone to take the place of a user who has plagiarized in a well-paying campaign. For example, I am someone who wants to get into a campaign but the campaign is full. I perform some research to see if there are examples of plagiarism with some of its members. I find one fall guy, I report a few of his posts, and he gets banned. The campaign then opens for new participants, so I apply and maybe get accepted. It's a long shot, but still.