ML/NJ
One can make a case that it is even worse than you think. In many jurisdictions challenged votes, provisional ballots, etc. are not counted unless the election is close enough that they might make a difference. It is not difficult to imagine a scenario where they would not matter on a local level, but nationally the totals could be closer than in any given state.
And, who tallies the "national popular vote"? New York Times? CNN? Fox? There sure isn''t any official government body that does this.