I disagree. I heard the story about the "Penny turtle" or "petshop turtle" which is a pretty lame one. The myth is that there's a turtle that stays small and you can keep it in an aquarium fairly easily. This guy knew how to find eggs, hatch them, and would sell the hatchlings to petshops. They rarely survived, and if they did they got pretty big. Someone interested in conservation spent years trying to track down the turtles, and once they found them and were able to monitor their population, he found they were endangered.
Similarly, Womas are considered to be endangered (or atleast rare), as are frilled-neck lizards and so on. Do you really think it would be okay for someone to decide they want a pet and wander into the bush to get it on the cheap? The licencing works to discourage as many people as possible from doing that. Sure you can't eliminate all poaching, but it helps.