Are you sure that these were not just a few cases that went shoplifting? In principle, you don't need a book to understand the law, every child learns and knows that you don't steal or cheat others. Not because it is written, but because people make this experience very real. For example, they feel anger about being robbed, and children who observe their parents grieving about a theft learn that the thief acted wrong. But perhaps in the distant past, before there was any thought of possession, there was no such thing, and if someone took something from you without asking, it may not have been stealing, because where there is no sense of wrongdoing, there is no accusation. Perhaps, as I can envision it in my imagination, something that someone else had lying around because he could not yet use it, that is, it was a kind of surplus, would be little or not at all angry if someone who had no surplus had taken something from the one who had more. Without a sense for "mine" something might have been a common good and then one might not even have had the idea to hide the taking away. I think I can vaguely recall a book - I don't know if it was fiction or a field report - that people were observed doing something like this and a simple object had made the rounds in a village, for example, until it ended up back with the one who "owned" it first.

For us "civilized people", such a thing is hardly conceivable, so far removed from our canon of values, so alien. But I find the idea very interesting, because it resonates with something...