You can find the answer to these questions and much more in Neil Stephenson’s essay “In the Beginning was the Command Line”. The essay is about mainstream operating systems (Microsoft Windows, Apple Mac OS, Linux), both from a historical and a psychological point of view.
The historical section is rather outdated: it was written while Be OS was still around and Mac OS X wasn’t; the informations contained in it are accurate and very interesting nonetheless. On the other hand, the description of the psychological factors that are behind the operating systems market and, more in depth, their interfaces, is still absolutely relevant.
Actually the psychology of interfaces and their users is the main theme of the essay: the insights about it are the best part of the writing.
The printed text file is about 55 pages long: this makes it a very good reading for train travels or similar occasions.