I suppose that is so that the FCC does not have the idea that they are adding to their own budget if they hand out fines... kinda of a conflict of interest?
But still, if the FCC is sending the letter and announcing the fine, either they are turning that over to some other department to enforce/collect it - and THAT department is failing to follow through, or the FCC is just sending the nasty-gram letter and never actually turning it over to whomever is supposed to enfoice/collect it.