You live in a modern society. These questions should be obvious to you: How do you organize the military defense of a country? How do you train, educate and fund a police force. Where and how do you stretch power lines. Regulating the usage of land.

And I never said all authority must be centralized. As noted before, it is a good principle to make democratic decisions as close as possbile to the people affected. If an issue affects a neighbourhood, then let the neighborhood make the decision. If it is an issue concerning a town, let the towns people decide etc.

I did not bake any oligarchy into any cake. That is just an empty assertion.