Australia has it easy: Indonesia and Malaysia have an estimated 100,000 illegal immigrants now, mostly not in detention nor fed and housed at taxpayer expense – as that would cost too much.
Perhaps we should try a cheaper approach too?:
1. A month to assess as not a terrorist or criminal with the publicised onus of proof on the foreigner;
2. If not, then comprehensive biometrics measured (or microchipped), prohibited from living in or near the major cities and flown to a range of towns like Woomera and Alice Springs with no dole etc. but allowed to get jobs and pay taxes.
3. After three to six months offered a seat just once on the next periodically chartered flight back home.
This would cost us much less than the current solutions and might even benefit the outback… Of course for real undesirables terrorists or crooks we pay Somalia or some such country to take them and put them up in their luxury refugee camps…