Technically, that is a different type of competition. That is an event at least partially based on skill rather than a pure-chance lottery. In places like Canada, and I suspect Australia too, such rules draw lines between competitions for prizes and a lottery subject to gambling rules.

I'd bet that a suburban mall couldn't got a gambling license, but a paper airplane throwing competition is something else. It may seem silly but that small requirement does negate many of the evils associated with gambling. You aren't going to see someone dropping thousands on lotto tickets if they have to throw a paper airplane each time.