to put it simply, the AFL got (will get) more because they have a much more broadcaster friendly game, this isnt exactly rocket science man, let me explain it to you.
lets just say rating are 50/50, one game goes for 2 hrs and the other for 3hrs, which game do you pick if you own a TV station to sell adverts on? also considering the AFL brand can sell an add after every goal (around 25/30 kicked per game, qtr time and 3 qtr time breaks.
payTV.
NRL has something like 60 of the top 100 ratings i hear, but fact is, AFL overall out rates league on pay, sounds stupid i know but its true, this is because AFL FTA games go head to head with AFL payTV games, BUT, the thing is, the replays of the AFL games massively out rate the NRL replays and with the extra veiwing time of an AFL game they rate higher on a veiwer to hr scale.
the NRL outrated the AFL GF last year, but when you consider that there was a melbourne team in the NRL GF and 2 relatively small AFL teams playing thats not surprising, also consider that the NRL GF was played on Sunday twighlight, fact is man, people who are in charge of spending hundreds of millions of dollars arnt stupid, channel 9 threw everything bar the kitchen sink at the AFL and still lost, also, that offer was a one time thing, theres no auctions for the AFL rights, chanell 9 have one chance, they must make there highest bid, because chanal 7 bought the last port of call for the next 10/15 yrs i beleive.
the AFL have there own fixture, something gallop himself said not less than 3 mnths ago would cost the NRL 50mill in broadcast rights.
in summery, the NRL rights arnt worth anywhere near the AFLs, its just common bloody sense man.