Surely the most likely route between Kilburn High Road or South Hampstead to other North London Line stations is a direct train, right? The only way via zone 1 while dodging all barriers is to go back to Queen’s Park, change at Oxford Circus then Highbury & Islington. Even for Queen’s Park or Kensal Green, the assumption that the passenger will take a direct train should take precedence over a change in zone 1 for the default route.
Direct trains have run on this route for years already, so there is no excuse for TfL not to set up the fare table to charge correctly on this route.