Why can't you buy hamsters in Australia?

Answer 1

Possibly because they could mutate, and become ten feet tall, man-eating, and deadly.

However, unfortunately it is far more likely that this is because they could escape, breed, and become a serious pest, similar to rabbits.

I've found no official reasoning as to why this might be the case, so it's merely an educated guess.

Answer 2

Because if they were released it would disrupt the eco-system of the country. It is illegal to keep a hamster as a pet in Australia.