Well Zombies are an inversion of the old horror archetypes of Dracula and aristocratic vampires. Used to be that what scared most people was the blood sucking old money capitalist in the manor on the hill, who follows strange arcane rules and has the ability to slaughter and exploit mortals. Most people were workers or peasants.

Now most people in the US are middle-class consumers completely absorbed into the cult of individuality. They see themselves as Dracula. They see the workers and peasants of the world as mindless and stupid livestock to exploit and slaughter. Their inside subconscious source of perspective and identity has swapped from one of the lowly masses terrorized by a powerful monster, to a powerful monster who terrorizes the lowly masses. Hence the glee you see when people discuss what they would do during a hypothetical zombie apocalypse and it's pop-culture power. No peasant or worker would have felt glee at the idea of a real life vampire apocalypse.