If businesses can't source the employees from the local market, they are able to employ and sponsor overseas applicants. Take a look at Doctors in Australia, or Teachers in the UK.
I find it very amusing watching ppruners celebrate that there is a pilot shortage, but like "phantom" says, "It's a global market.
The minute Airlines have advertised and are unable to source crews from within Australia, They will go OS.
I am not agreeing with the situation, but I gained a work visa from another country and that is how it works.