A/R obligatoire???

Réponse à ma question ; officiel :

It is possible to enter Australia on a one way ticket. However, you may
need to satisfy the Immigration Officers at the airport when you arrive
that you have sufficient funds to support yourself as per the requirements
of your visa. In addition to these funds, you will need to provide
evidence that you have sufficient funds to purchase a ticket out of
Australia. Proof of funds can be demonstrated in the form of the most
recent bank statement you have or any other proof demonstrating available
funds.