Electronic Travel Authority
Checking the validity of a person's eligibility to enter Australia now is almost impossible to do by looking at the passport. The old printed visa that the Government used to issue, has been replaced by an Electronic Travle Authority (electronic visa if you like), that is tied to the individuals passport number. As visual check will tell you nothing. Its all to do with the ability of the check-in staff to process these passport numbers through the SITA network at the CUTE2 enabled leased check-in desks. Installation of passport readers at the check in may alleviate most of their mis-keying issues. $10M would have bought them 3 times their international requirement for these devices.
Of course the main reason for getting the hard-copy visa out of the passport was that it was discouraging tourism and Australia was recieving tit-for-tat responses from some Governments, including the USA and France. It was a really neat trick to make it all electronic and tie it to the MRZ of the passport - however, the flip side is the lack of anything humanly readable.
The airlines are fined the equivalent of the cost it takes to fly any illegals back + admin costs. Totally reasonable - if you can get away with it.