The reason why zombies don’t eat each other is because of their flesh. Their flesh is putrified, and so they only crave warm flesh from the living. I would certainly change the way a zombie moves or attacks, I loved how in the RE:4 videogame the “ganados”(as they’re called), could team up into small hordes and attack you. The ganados also used malee weapons and of course THE BLOOD-SMEARED CHAINSAW!!! I would like to see that in zombie films someday, instead of the old mindless walking corpses that we are seeing today.