then it became the fear of "totalitarianism" turning everybody into a mindless horde, then the critique of consumerism we see in the romero movies, and after that we see the shift to the post-apoc survivalist genre. with zac snyder's romero remakes representing a decidedly libertarian and reactionary take on the subject, whereas train to busan does the based thing and turns the zombie apocalypse movie into a socialist parable about the vital need for collective action and altruism.