Umpires in AFL or officials in other sports, it doesn't matter because you still find the same situation popping up. You have full time professional athletes competing with a part time official in control of things. Players get annoyed and the fans get annoyed. The thing is the AFL probably has the resources to spend on the umpiring department to make improvements.
What frustrates me mostly in AFL is the number of times the play is intervened by a non controlling umpire. In some cases they pick up the free that should have been payed, which makes you question why the controlling umpire didn't see it.
Its the calls they jump in and make from the furthest perspective which should have been called play on. That's annoying.
The only possible fix I could see is if they can reduce congestion and the amount of players around the ball, vision might be better, the game might be a bit slower and easier to pick out the calls.