It's not a mistake though. "just don't have the survival skills to survive outside a civilization with microwaves and working plumbing." It means that they do have the survival skills to live in a civilization with microwaves and working plumbing, but in no other context. It would need to be "without" if the sentence was "just don't have the survival skills to survive in a world without microwaves and working plumbing" but that's not what the sentence is.