It's not always that the drivers are not there, it's that they're often there, and want to cherry pick the races they drive in, telling the judges not to list them in lower classes or late races.
How many times in the seventies do you think a trainer was told to choose between Russel Rash, Frank Tagariello, and Gerald Procino, because Carmine, Herve, Lucien, Buddy and Benny were there, but didn't want to drive in a B-3 or the last race,,, That's standard operating procedure now at M1.