Originally Posted by
queensgambit
Unfortunately matrix can be wrong. Usually it misses an esoteric routing rule on a complex itinerary, but that's obviously not the case here.
Odds are Matrix is forgetting the fuel surcharge (TATL fares are typically this low, along with a $500+ fuel surcharge). It could also be an issue where the Q bucket is unavailable or ineligible for one-way booking, but I would bet on it missing the fuel surcharge.