I understand that it is commonly believed that cooking recipes and "software recipes" (source codes) differ from other kinds of potentially-computer-memorized-data (such as a romantic song or a romantic book and so forth).
How does a cooking recipe and a software recipe (source code) differ from other kinds of data in general and works of art in particular?
Why are they more subjected to "copyleft" approaches than, say - songs, books, movies and series?