Except... the key feature in a lot of those works is that the protagonist is completely unprepared because they miss (via plot device) the start of the end of the world
Precisely. Zombie apocalypse and/or apocalypse stories tend not to be about people who have been waiting for the inevitable, but ordinary people who have risen to the occasion. Walking Dead's
protagonist was a cop, Falling Skies'
a history professor.
And sometimes they make the point that misanthropic behaviour, though couched in language of being the 'right' thing to do, can just be the self-justifying ranting of a disturbed mind.
There is a whole fandom built around the question of 'what if' there was a zombie apocalypse and 'being ready' for it, which is just an odd hobby, I guess.