Why are ferrets banned or outlawed in many countries, but not cats, rats e.t.c.?

Going on the basis of protecting native wild life etc, why aren't cats and rats banned? I mean, out of the 3, cats followed by rats are more likely to survive in the wild than ferrets. They're more likely to cause harm. Cats can climb, while ferrets can not. Cats are moe effiecient hunters as well. Rats can also be very destructive. In my country, I have to go through A LOT of legal work to get a neutered ferrets. It's neutered for crying out loud. Yet I know guys who managed to get Capuchin monkeys into the country without trouble. WTF?!