Comment by dcow

It's not obvious at all! You are citing the only difference that typically comes up. A quesadilla is beyond trivial to reproduce and most people have the ingredients readily available. 3D printers make it trivial to reproduce things that would have been obviously hard to reproduce a few years ago. A book is hard to reproduce if it's not in digital form. Is MIDI a song or a set of instructions? Source code is easy to copy but hard to reproduce. Source code is just a recipe telling a compiler what to do. And we've already established that recipes aren't copyrightable because it was "so obvious" at the time copyright was established that you shouldn't be able to copyright the creative process.