Ok, I understand your point of view- I really do, and I get that it is our responsibility. But the problem is:
1. There are other people on the island.
2. How do you know who robbed you? I am very careful, EXTREMELY careful, about who is trusted, (and I just got robbed again, someone took all the valuables from the Xmas presents I made for my friends, along with out entire beacon pyramid and beacon), but I do not know who is doing it and there is no way to tell!
It seems like if there were a simple way to prevent stealing, it would be put into action. I understand that it is our responsibility, but if there IS a simple way, why not?