Charlie said
When you see some examples of plants
getting out of control in Australia and New Zealand you can
understand
why they are a bit twitchy about letting gardeners import what they
like!

When you see some examples of Australians getting out of control you
can understand why they have to go through quaranteen and customs to
enter the country
Though I doubt many do get quaranteened, but they do have to go
through imigration, (as does my wife as she is Canadian),
David