The semiconductor manufacturers have numerous Trade Secrets concerning how they achieve high circuit densities and high yields in manufacturing. The vendors of software sell use licenses and provide copies of compiled code and documentation to licensees. The authors of books transfer their copyright to publishers via contracts with specific terms for publication, marketing and payment. Purchasers of books may read and re-read the book, let any number of others read the book, and even sell the book again. Composers of music often make similar arrangements with distributors and moreover, receive payments for each performance of their work.
Actors usually secure intellectual property rights to their recorded performances, too.
Software, books, music and films are not secrets because their commercial value is realized only by making them available. In contrast, techniques of semiconductor manufacturing require secrecy to assure their commercial value, since their use by others can often be concealed long enough to compromise the owner's advantage. The value of intellectual property generally declines over time. The novelty wears off, the market is saturated, other products and inventions successfully imitate or improve, etc. Thus in our increasingly entrepreneurial world people have become increasingly protective of their intellectual creations.