It has no drug problem because if you do drugs you’re going to prison for a while then you’ll get out and never find a job doing anything other than cash jobs, probably not even that. Your life will basically end, your family and friends will abandon you, and that’s about it. The borders don’t really have much to do with that, it’s an island anyways.
The zoning is the key to the fact that there’s plenty of construction but they also have a declining population, so that helps.