In his book a culture of star-faring traders are pitted against a stratified fascist culture with castes. He examines the blind spots of each culture but sends a clear message that trades have a kind of moral high ground.
He doesn't explicitly examine or seem to understand WHY.
Traders must be ... tolerant. At some deeper level they want the pie to expand. They want to make money not tell you how to live. They can't derive any profit or pleasure from simple control or domination.