In my experience, when pay is through Arbiter the game administration on site should be responsible for that paperwork...not the officials. Its noticeable when you expect 4 officials and get 3, so its easier for the game admin to ask "whos not here" than to require paperwork from the 3 that showed up and try to deduce who didnt.
From a guy that's been doing this for 27 years, I can assure you, the dweeb in AP will have no idea who did not show up and will simply pay whoever is in the system.