That machines exist that can detect nanograms of drugs is irrelevant. It's like saying you can take photos from your satellites with resolution capable of counting ants and then positing that this will stop all auto theft. In practice the detection thresholds and circumstances can be circumvented by the use of swarming technologies.International vendors are like credit card companies encountering card fraud. They expect to "lose a few". The majority of what the Australian postal police and AFP have to say about drugs in the mail is posturing.