It is not as if Moderators get paid to do what it is they do. This is a very large, if not the biggest Black Hat SEO forum the internet has to offer. Last that I checked, new methods are being posted every day. Along with new methods you have reports, false reports, BST requests, flame war threads, the sections we do not even see (Junior Executive VIP, Executive VIP, and who knows what else when you reach that level), the downloads section, all threads being supervised to make sure they are in the right section, spam thread removal, and infamous shit list threads. Consider the amount of personal messages moderators receive per day. With a focus on the more active moderators.
With what I said above, with new users being registered every day too, and manage things besides the moderator's normal & business life takes some work. With the amount of success an HONEST (not pointing any fingers) BST thread would make, it is a privilege here to have. $30 per year is not any sort of damaging amount to a members income if that member being here for a few months and trying some of the literally free money making threads that are on this forum.
With all of that to manage, there are going to be threads that get passed a moderator's detection. I admit, an approval process may need to be more thorough, but that is coming from someone who is not a moderator. So you may take that with a grain of salt. What happens when a scam/bad thread makes it through the moderator's approval process? The thread does not do well, gets flagged, and removed/closed within a few hours to a few days time. The moderators do their jobs here. They even take the time out to answer stupid questions we have that are covered in threads and in the rules.