You don't need a degree to understand that it will cost a lot more than 5 cents to fly on these sectors.
Whatever the seat/km cost is it is a heck of a lot more than 5 cents.
Add to that the cost of the various taxes which we all normally pay and someone is subsidising the cheap fares and to a considerable amount.
Jetstar's ASK per seat is around 7.9cents per available seat km. Therefore read above post to get a real understanding.
"Wouldnt have thought it was heck of alot more"
Obvious you need to understand the financial operations on how it really works....