One reason is that patents are much broader than copyrights. A copyright only prevents someone from copying your specific work. You can copyright Batman, but so

One reason is that patents are much broader than copyrights. A copyright only prevents someone from copying your specific work. You can copyright Batman, but someone else can make Black Panther. Patents cover independently developmed products and can cover fundamental methods or products. Inventions are often nearly developed by diffrent people. If the Wright Brothers didn't invent the airplane, someone else would have within ten years. Someone else wouldn't have written To Kill a Mockingbird. Some other novel may have captured the same fame and critical praise, but that copyright doesn't stop that novel from exisiting.