I read it as "young people employed as professionals can make more money by being not-professionals in the Australian outback".

But to many, "professional" merely means "someone who is paid to do something". I think that usage came into the popular consciousness via "professional athlete", though I'm not sure if that's the first instance of the popular usage.

ETA: according to OED, the relevant distinction in this usage is "professional" vs. "amateur", and it was used somewhat in that sense as far back as maybe 1806 (I assert that their earlier citations were meant ironically, or merely by comparison to actual professions).