The ride computers automatically add the number of seats on each train dispatched to the total rider count. The driver counts the empty seats during dispatch and subtracts them from the count, giving a very precise record.
^I dunno...are Millie's CoasterMania rides included in that ride count?
I will say, some sparse morning ERT D-back sessions are a very loose atmosphere...I could picture the driver being careless on the only 25% full trains.