I wouldn't say scoring is trivial -- it depends on both players agreeing which stones are alive or dead. Experienced Go players "just get it" but computers don't: http://www.andromeda.com/people/ddyer/go/scoring-games.html
AGA Rules: 9) Ending the Game: Two consecutive passes signal the end of the game.
New Zealand rules: The game is finished when both players agree that there are no more worthwhile moves.
Humans agreeing on a score and outcome has little to do with what a program has to do to calculate this score.
I still don't see your argument. Humans and humans are capable of agreeing on a score with those rulesets. Computers are also capable of following the ruleset and agreeing on the score. Computer vs. human games are not playing by a different ruleset. By that ruleset, the game is over when both sides pass.