Not Paying
Unlike many people here, I almost never do "search" and "link." But if someone wants to take the time, prior threads have included the language from the law (the one which creates and authorizes the existence of the FAM program) which states that the airlines must carry FAM's with *no* compensation.
(For the benefit of our new member - just about every FAM, who has posted here, has reported receiving the same inaccurate information - that FAM seats are paid for. So I am not disputing what you were told.)
Also, earlier threads have pointed out that the airlines get *no* tax benefit from those "free" seats.