The law is just an agreement with a large group of people that says "don't do anything bad and we'll watch out for you". These people have just replaced that wi

The law is just an agreement with a large group of people that says "don't do anything bad and we'll watch out for you". These people have just replaced that with their own informal arrangement. They probably prefer their got-your-back arrangement because they trust their neighbours more than they trust people outside the community. In addition it tips the scales in their favour because their law doesn't need to protect everyone equally. In this case outsiders are not afforded the same benefits as islanders. They just need a reasonable belief that they won't be steamrolled by the actual law, which comes from having a tight knit community where people don't run to the police. You see the same pattern amongst cops, the mob, remote communities, etc.