I myself am willing to moderate for free if I were will be given a chance. It's not just about the pay, I'm more concerned about the reputation.
If you are willing to gain reputation of the community by moderating a sub-forum then its totally a bad way of gaining trust from fellow members...
Sorry mate, but you have misunderstood what I said, its not necessarily on a users account but the reputation of the board that can be left behind without any moderation. And also I don't think being a Mod will give us that kind of credit besides you were already a reputed and trusted member if you were picked to do the task.
Moderator position is simply being given to users whose already a trusted member here with enough contributions to the forum, I doubt it will be random pick LoL. So basically it can't be like that.
Additionally, I get what your point here but considering not all user are willing to do the task for free.