#7.They Have Too Many Natural Predators - World War Z and the Zombie Survival Guide point out that the reanimating component (Solanum virus) makes the host inedible, and fundamentally alters cellular biology in the host.
#6.They Can't Take the Heat - see #7, altered biology.
#6.They Can't Handle the Cold - see #7 and think "cellular anti-freeze"
#5.Biting is a Terrible Way to Spread a Disease - Read "The Walking Dead". The disease effect or whatever it is is already present. The bite just causes death and reanimation more quickly.
#3.They Can't Heal from Day to Day Damage - yeah, but they also don't suffer catastrophic system failure from localized damage, either. See #7
#2.The Landscape is Full of Zombie-Proof Barriers - Again, the assumption that bites are the only way for the disease effect to transmit is incorrect. If it is airborne, or even some sort of strange energy field effect, it can manifest instantly everywhere. Also, these barriers work against any survivors who are probably devoid of most travel technology, at least over the long term.
#1.Weapons and the People Who Use Them - this is basically the assertion than human beings are fully-armed killing machines with a thin leash, and they would wipe out a plague of parasitic human being who look like loved ones, and should apparently react to reason and love with compassion and non-homicidal understanding.
I point to the species Democratus Americanus as all the proof I need that we would allow ourselves to be systematically over-run by a parasitic sub-species of the living-dead, instead of exterminating them as logic dictates.
Frowning takes 68 muscles.
Smiling takes 6.
Pulling this trigger takes 2.
I'm lazy.
