Z:gnu-www-ja-google-engineering-talk--21403d-Software is an example of a pr/en

Software is an example of a practical, functional work. You use it do to a job. The main purpose of a program is not that people will read the code and think, "boy, how fascinating, what a great job they did." The main purpose of software is, you run it and it does something. And yes, those people who are interested in software will also read it and learn, but that's not the main purpose. It's interesting because of the job it will do, not just because of how nice it is to read. Whereas with art, the main use of art is the sensation that you get when you look at it or listen to it. So these are very different ways of being used and, as a result, the ethical issues about copying and modification are different.