...these aussie carriers...
If you're talking about Jetstar or Virgin then it's a requirement to have an endorsement not an "advantage". I don't believe it makes any great difference in the interview whether you already have one or not but between being told "yes" and actually joining the company you will have to get an endorsement on type. It's a little bit better now that you don't have to pay upfront and can salary sacrifice the cost but you're still paying for it.