A few years back, all my packages coming from the US and Canada where being inspected by Australian Customs, every parcel for many months had one of their calling cards enclosed. I was also getting feedback from some other modelers that they were experiencing the same.
I bought a large batch of Canadian hoppers from PWRS, when they arrived I was asked to go in and collect the package. After I had collected it and been cleared, no duty to pay or anything like that, I asked why the scrutiny? I was told that toy trains were being used to carry contraband, not so much on the East side of the country but they were seizing a lot of product in the West. I did not challenge the toy trains description.