The people in this universe don't understand the idea of a corpse getting up on it's own and walking around on it's own, well having a desire to eat. The point of this series is people coming to terms with that reality, at the moment the idea that these people are simply "sick" and could be "saved" is something many think is possible. This series is really about watching society and it's remnants come to terms with that reality.
Zombies are only part of my issue with the core family characters.
Who casually saunters to the car after and gives their parents attitude for wanting them to hustle after they saw a zombie the night before? Who wanders away in the dark after having just witnessed their neighbor attacking another neighbor's family? They're not weak. They're stupid and annoying. I don't like any one in the core family. Who leaves the door open? Even if there wasn't a dog that appeared with blood all over it, it's just good manners and a regular thing that people do. Who turns their lights low to hide the fact that they're home but flashes a flashlight at a window when the power goes out?
I'm okay with people not knowing how to handle a zombie encounter and struggling with whether or not people can come back to being alive, but a lot of the tension they tried to create in this episode are all things only someone conceited and super stuck up or incredibly stupid and ignorant of basic survival 101 would do. Don't like the characters. Well, the Spanish speaking family is okay and interesting.