McCarthy does eschew the traditional rules of punctuation and grammar in writing The Road. His motivation certainly could be to display the bleak and depressing mood that carries throughout the novel. Consider this, though: Perhaps he is using this lack of punctuation and ‘rule-following’ to impress upon the reader what matters and doesn’t matter in this world he has created. The father and son go for a year without speaking to another human, there are no birds, and there is a lack of trust amongst these remaining humans. Does punctuation really matter? I think this is one motivation of McCarthy’s: to challenge our thinking about what really matters to us. Perhaps he didn’t see commas and apostrophes as that essential in telling his story.