That's pretty much how most people think in the USA too. In fact, the vast majority of computer users are either unaware of or unconcerned with the existance of other OSes. Most are aware that there are a handful of people who prefer Mac, and might have heard or read the word "Linux" before, but have no idea what it is or even care. If you were to ask the average American to list all of the OSes he knows (first you would have to explain what an OS is and add the phrase "like different versions of Windows" on the end), he or she would most likely answer "Windows XP, Windows 98, and Windows 95".
The same is true of open source software (with the possible exception of Firefox). Most Americans are not aware of the existance of open source programs or even what open source is. Firefox seems to be the only open source application that has made any headway in reaching the "technologically inept", "computer illiterate", and the "mindless M$ drones" . I'm hoping Open Office will soon reach the same point, but it still has a ways to go. Whenever I mention Open Office to someone, I have to explain what it is by comparing it to MS Office, explain who Sun Microsystems is, and give them a general idea of what open source software is and how it is different from commercial software.