If you have no intention on flying on Jetstar, why worry?

Qantas can apply carrier surcharges since the government has not prohibited it in Australia

Seems that QF is applying a $29 surcharge for the booking

Looking at Expedia's pricing, it appears that Jetstar absorbs taxes in its fare since Expedia is only showing a GST componant as taxes

There would seem to be taxes of $7.41 plus $1.81 to pay on a Qantas award which is $9.22

It would seem that Qantas is charging $20 in carrier surcharges for that route since $20+$9.22 + 10% GST would come ou about right to what is being quoted