What is this retardation?
The core books say that the majority of civilised worlds are hellholes. Each and every one of the main rulebooks of each edition said that the overwhelming majority of the people in the Imperium are overworked and live short lives of grind and suffering. All to sustain the Imperium.

By the way, civilised worlds doesn't mean "Earth but in 40K". The core books count feudal worlds, hive worlds, et,c into that category.