Douglas Noel Adams has successfully tried to show us another aspect of our daily-life routine. By using many cynical elements, he creates extremely funny situations which represent much deeper aspects.
The destruction of Earth in order to create Inner-Galactic Highways as the definition of Earth in the universe encyclopedia both represent the smallness of human-beings, contrary to their original conception.
Furthermore, the alien breeds are not perfect at all, many aspects of their actions represent a similar action which is often taken by humans: The destruction of earth without an announcement, is an equivalent of the house-destruction of Ford Perfect, one of the story’s heroes, without announcing him, both are explained by the governments as actions for the welfare of the population at the cost of suffer for a single person or for a relatively small group of persons.
Adams uses every opportunity to attack the ignorance of humankind, especially the bureaucracy of the government, wherever they are, even if they are of alien breeds.
In conclusion, “The Hitch Hiker’s Guide To The Galaxy”, besides being funny, gives us a very special snapshot at the inner-world of Adams, and makes us think of what we have taken obvious, in a different way