If you can't supply one the logical conclusion is that there is no good reason and all the reasons that flow from simple observation are terribly unsupportable morally and legally. You know that. You are vague because giving a better answer is impossible and the actual answer is unpalatable.

Yet the reason is an important subject, and in questions like that different reasoning lead to lost lives. So it's a serious, justifiable subject to discuss.

I don’t find abstract philosophical arguments convincing.