Even so most people know that the quickest way to kill something is to shoot it in the head.
And yet they are by and large trained to aim for center of mass, because that's where most vital organs are and it's a bigger target. It's not like they never shot anyone in the head. The cops on that first night eventually shot the walker in the head, but only after he bit a few people. And the cops in the street just before the riot were shooting in the head. You people just have no idea how you'd behave in a world that never had zombies because you can't actually separate yourself from your existing knowledge. What if killing a person by smashing their head in even though they can't harm you because they are separated from you by a fence results in someone being arrested and charged with murder? What if while smashing that person's head in you come in contact with their blood, will you get infected? What if there IS a cure, do you want to make that irreversible decision of murdering your neighbor?
I really don't get the 'all the characters are unlikable' thing.
Kim - high school guidance counselor. She went out of her way to try to keep a kid from being suspended/expelled when she knows he's not really a threat to the student body. She has a kid who is a long term drug addict and has been kicked out of every rehab facility in the area. She's stressed from the school work, she's had her son missing for days (weeks?) and when he shows up he's in the hospital after being hit by a car. She's over it, as any parent would be after a child has repeatedly gotten himself into legal and medical issues with his drug addiction.
Cliff - teacher who is trying to build a new life with his fiance who has troubled child. He wants to help any way he can, and when seeing the son for the first time in a medical situation (or only a few instances) does what he can to try to help him. He believes the kid had a bad experience, and wants to trust him, but in doing so also wants to verify what happened. He risked his own life to help the woman he loves with her son by going to a drug den. His own son, when he knows he's at risk, tries to get him out of the riot zone. He's slow to accept what is happening, but that's not at all unusual when this is the very first time in history in their world a zombie epidemic has started, and he's going into the situation as anyone else would with ignorance of reanimated people eating corpses.
Frank - druggie kid. Everything that's happening to him is his own fault. But he's like any other drug addict, self centered, flawed, a real pain in the ass. He's going to worry about his next fix more than anything. Because that's what drug addicts do.
Alycia - over achieving teenager with a boyfriend. There's nothing about that description that's going to make her parents have an easy time. Teenage girls are the worst. They are made worse when you lie and conceal important evidence like the dead coming back to life to kill people.
Lorenzo - he's a teenage boy that thinks everything in the world is about him. Teenage boys are the second worst thing. Thinks that everything he does is important and he's changing the world by everything he does. Doesn't even bother to answer his father's phone calls. He's a ******, because you know what? Teenage boys are douches.
Ruben - protecting his family after getting out of war zones. He's pretty much right about human behavior, and how he's trying to protect his family from the really bad situation coming down the road.
Tobias - teenager who actually pays attention to the world and isn't so stupid to think the government is going to tell the people everything that's happening. Smart, but extremely frightened by what's coming, and knowing how he's likely going to die along with his family very soon, but at least trying to do what he can for his family. Tried to protect the one person at his school who tried to help him with a pen knife.
Seriously, these are average people in an extraordinary situation. They are behaving more or less no different than most of you would in the same situation.
