As someone who is a biologist in Australia, oh my god is it a headache to get seeds into Australia. Lots of paperwork involved if we actually want to grow overseas plants, much easier to import extracted RNA or DNA (but way riskier for the research, shipping companies aren't trustworthy in keeping smaller shipments on ice).
The dogs and the x-ray at the airport are not for drugs, they're mostly biosecurity, too.
I can't see something like the OP happening in Australia, it would get destroyed at the border
Fellow Australian here, and I've always viewed our biosecurity as being pretty tight and effective, too.
Apparently however small innocuous packets/letters don't receive quite as much screening, as I've heard of people getting marijuana seeds in the mail just fine.
Considering how one or two seeds can be enough if the purpose is simply to acquire the species it seems like an impossible task to prevent that.
It's far more difficult than drug smuggling which only works in some reasonable quantity - and becomes more like information smuggling in biological form where you only need one copy.
"The precedent-setting agreement classifies a spacecraft as an export. Once launched, satellite components were judged to be “severed from the possibility of trade within the United States” and therefore considered to be exports, according to Customs officials."
Meanwhile New Zealand looks at Australia, pulls out their own biosecurity system and says "That's not a biosecurity system. That's a biosecurity system.
NZ is the only country I know that makes you take your shoes off in the airport... in order to scrub and bleach them (to be fair they were hiking boots, though not obviously filthy). What service!
True, but NZ has also learned it the hard way. There was once a vibrant birdlife in the South Island, especially. There is some early settler who said that the morning birdsong in Queenstown was deafening. Cats, introduced by European settlers, killed off a lot of the native birds, and the ecosystem is only recently hobbling back to normal (have done birdwatching in NZ).
If you are interested in bird conservation in NZ, please visit Karori park in Wellington and contribute.
BTW: some parks in US also have installed brushes to wipe your boots for preventing the transmission of invasive species seeds. I think there are a few in Wisconsin that I remember.
Some preserves in California have trays of disinfectant to step through, specifically for Sudden Oak Death. It’s a pathogen transmitted through dirt, so in the very few places that aren’t affected yet it’s hard to keep out.
It is because of our early history - heavy with hubris - with introduction and escape/release of cane toads, prickly pair, tiger pear, rabbits, foxes, camels, fruit fly, etc ... that Australia is now extremely cautious.
https://en.wikipedia.org/wiki/Biosecurity_in_Australia