True. Which is why non-personal things based on personal relationships often fail. Because it's too easy to cheat, and even those otherwise disinclined to cheat often find it quite tempting because it distances the person from the act.

This is almost solely a psychological issue, and it's doubtful that any sort of technology can overcome it. The only thing that I can see that even comes close is attempting to make sure that there are no duplicate people, but even that's fraught with other problems.