The producer credits in Curb Your Enthusiasm

I’m not sure if this has been answered before, but… what’s with all the producer/executive producer/co-producer etc. credits at the end of Curb Your Enthusiasm? Is it just the old inside Hollywood joke about promising any jerk a producing credit in exchange for money or a favour? I think I remember reading something about it being a union thing, but can’t find a thing on it now. Little help?