Aircraft, It's a simplistic model so that simple minds like yours can understand.
You said it yourself that most of Skippers work is mining FIFO work. Therefore all aircraft are running around at 100% load factor whether or not they've got passengers on them, the mining company are paying for the whole aircraft. Really its an increase to the client of $125 for the charter but I would assume that most clients would break that down and put it into per passenger terms, ie $125/60=$2.08 per passenger. As Wizofoz said it proves that your $500 per passenger was a tad unrealistic and that was all it was meant to do.
I think you'll find that many of the Skippers and Network pilot's are doing at least 800hrs per year. I'd be interested to here some actual figures. The one person I know over at Network is on about 850hrs per year and I don't think he's any busier than the rest.