On the Atreides home planet of Caledon water is everywhere there are vast oceans rivers and rainstorms so the people living there can consume a lot at virtually no cost. 

On Arrakis, although water is extremely scarce, it's expensive. Even wet towels from the palace are sold to Fremens with whatever moisture that can be wrung out of them. This is a fantastic lesson on subjective value.

The average price of a good or service is not based on the amount of labor or the cost of the resources required to produce it. It's a function of supply and demand value changes depending on individuals desires and preferences and it's based on the availability of whatever it is that they want relative to how many other people happen to want the same thing at the same time

For eg- if you are thirsty and have a bottle of water, you are very less likely to give it to me or maybe charge a lot of money. On the other hand, you might have 100 bottles and may just give them to me for free.

Contradictorily, spice(the most expensive thing in the universe) is only found on Arrakis.

Still, much of the Arraken population is materially poorer than a lot of people alive on earth today. 

The reason is the political system in Dune: Imperial Feudalism which means the entirety of society is controlled by a private political party and since the territory is vast, some power, in this case, is delegated to Dukes and Barons.

The people of Arrakis, are also not legally allowed to own productive land or keep the proceeds of their work.

It means the state should play a dominant role in the economy, in particular by controlling commercial activity Everything the citizens of Arakis produce belongs to the Emperor and It decides what to do with it and who profits from it.

The government directly supports favored companies or

corporations and inhibits competition. They typically do this through tariffs subsidies and regulations that restrict

who is allowed to participate in commerce.

The company responsible for melange is CHOAM aka the honorable union for the advancement of mercantilism in which the emperor has directorship.

As a result of the policy, the people of Arrakis have no purchasing power with which to flood their entire planet with water food, and other resources they could have easily acquired in exchange for their magical

spice.

In a world where individual rights are universally respected, we would see a multitude of property owners who become entrepreneurs, who genuinely create value for others which ultimately enrich the lives of even more consumers, and equally importantly everyone would

be allowed to keep the income they have legitimately earned using it to improve their own lives as they see fit