I just read this and looked into it, because it was news to me that capybara are ‘banned’.
It’s half-true, really. The relevant legislation essentially declares all land vertebrates that aren’t native to Australia as prohibited in Victoria by default (this is Schedule 1), and then there’s a schedule of species that are permitted to be kept by zoos as exceptions (Schedule 2). Looking at the list of exceptions I strongly suspect it was defined rather simply by which species were kept in captivity in Victoria and potentially the other states at the time the legislation came into effect (with possible additions or subtractions since, I didn’t go deep down the rabbit hole).
Capybara are not listed under Schedule 2 so they are in this sense ‘banned’, but that can be easily changed by ministerial decision, and the Minister needs to consider the objective risk of establishing a wild population in making any decision. It’s pretty hard to make the case, I’d imagine, that capybara are inherently more likely to establish here than mara, for instance, which are much more suited to most Victorian habitats and are allowed in our zoos.
Unless there’s been a previous application to have capybara added to Schedule 2 that was rejected, which I’m not aware of, I reckon it’s just a case that no Victorian zoo has felt it worth going to the trouble to seek a change in the regulation that would permit capybara to be kept.