Based on my experiences at Nats, we will call no-shows up to the stage with the warning that if they don't come talk to us they will be dropped. The number of no-shows last year (the first with the PP requirement) compared to two years ago was significantly lower.
And yes, I was referring to resistance issues.
I don't know the infrastructure around awarding byes, however I do know that once the round is paired you can't go back and make changes - without a repair (I'm sure there's a certain fellow out there that seems to know TOM better than the folks who created it who would disagree with me, but that gets into opening the source files for the program and is frowned upon to begin with.) At that point, why repair to grant byes when you can repair to pair?
On that same note, why would those players deserve the perfect resistance of a round 1 bye? When we got down to tiebreakers going into top cut, having someone say "Well, if my round one opponent just hadn't shown up and the people at the event had arbitrarily given ME the bye instead of that other guy, I would have made it," again, hurts the integrity of the event.