Yes, overwhelming majority can easily be wrong. That's not surprising. And islands still have to watch for random boats from any direction. Right now in Vietna

Yes, overwhelming majority can easily be wrong. That's not surprising. And islands still have to watch for random boats from any direction. Right now in Vietnam there is a little outbreak where a group of Vietnamese nationals illegally crossed the border by a fishing boat from Cambodia to Phu Quoc island, trying to avoid the mandatory two-week quarantine. Then they boarded a plane, arrived at their homeland and tested positive. Immediately their steps were traced by police, whole Phu Quoc is under a mask mandate, 3 levels of contacts are tested and in quarantine. It really isn't about being an island. That's a myth, you've been lied to. If you want an example closer to your home, look how hard it is to seal a land border with Mexico. They actually cross by rivers, so water makes it easier.