There are actually plenty of Raaus aircraft incurring ASA fees given the increasing number of Raaus schools running in Class D, such as Moorabbin and Bankstown.
If you are using airports and the operators are not able to invoice you for it then something has to give as you are depriving them of income whilst utilizing their product or services. It would be like going to a gym and not paying or using a swimming pool by walking in unannounced. I suspect Avdata would do what car-epark operators do in Victoria and obtain a court order to retrieve the owner's details once they are ready to do an invoicing run.