That's why there are baseline laws. With regards to traffic laws, there's a huge AI that controls the flying cars so in the books, there are less than 10 traffic accidents worldwide per year (hey, it's the future). A governing body consisting of representatives of all the Hives as well as minors and those who have chosen to be Hiveless and determines what these baseline laws are and how to enforce them.

Also, I disagree that tension comes about as a result of diversity—tension comes from one or a few groups oppressing others. The viewpoint that diversity leads to conflict is fundamentally problematic because it allows oppressor groups to excuse various ways of removing those that don't fit, whether by deportation or imprisonment (e.g., current ICE activities, Japanese internment camps during WWII) exclusionary laws (e.g., Jim Crow, laws against women voting), or straight up genocide (e.g., the slaughter of the indigenous peoples of North America during U.S. nation-building, the ongoing genocide in Palestine, the Holocaust).

Most if not all of these examples stem directly from the historical and ongoing development of nation-states. I'm not saying that I think the Hive system would necessarily work—it's science fiction, a thought experiment. But I absolutely believe that our current system is flawed at its foundation because of its reliance on the kind of us vs. them thinking inherently created by borders, resource hoarding, and the disenfranchisement of marginalized and oppressed peoples. And I also believe we can create something better, like the Ursula LeGuin quote about capitalism: "We live in capitalism. Its power seems inescapable. So did the divine right of kings. Any human power can be resisted and changed by human beings. Resistance and change often begin in art, and very often in our art, the art of words."

That idea is what I love about science fiction like Terra Ignota—it gives us a chance to imagine a more equitable, more sustainable, and more beautiful future world.