Just the Rules: A Finished Game Gets Scored as a Bye?! | US Chess.org
Then there is the possibility of a tournament with both US Chess-rated (all games to be submitted on the rating report) and not-rated (never to have any games submitted) sections. If TD error accidentally paired a not-rated-section player in a ratable section then that game does not satisfy the expectation that both players thought the game was in a ratable section.
Or the case of a spectator sitting across from a player whose opponent did not arrive. Such a game was not paired, should not have happened, and it may not be possible to get information about the departed spectator.
So why should a TD have to pay fixit bucks for a good faith mistake when they are not supplied a service for tournament signups by USCF?
Because you can’t separate the ‘good faith mistakes’ from the ones who just don’t want to bother to check memberships.
There are TDs who have wound up paying the $10 fee for the same player in multiple events within a few months.
Many, though not all, tournament venues have net access (or cell phone access), so there’s really not much excuse for not checking someone’s membership status when they register onsite, or during the first few rounds.