Long and short of it is this: black markets have fundamentally higher barriers to entry and substantially higher costs. An AR-15 in Australia costs as much as

Long and short of it is this: black markets have fundamentally higher barriers to entry and substantially higher costs. An AR-15 in Australia costs as much as a very very fancy car. Moreover, the people who will sell it to you are deeply risk averse. Sure, criminals will have them, but it will be an entirely different class of criminals, specifically, those that benefit from low "random violence" environments.