I guess, well, it's that they don't even use electricity for the most part!
I watched a few episodes of "Walking Dead" until I realized it was a program of zombie target practice, gore and disgusting opportunities to teach the viewers a social lesson.
However, be that as it may, it became apparent early on that there wasn't any electricity because all the power plants were down. Apparently zombies have no interest in working.
During my 40 years running a power plant, I did observer a few operators that appeared to be zombies until they sobered up.
Al - K8AXW