It is illegal to copy other's work like songs, writing, and drawing. Some famous authors or singers make use of other non-influential authors or singers' work without authorization which may cause a great loss to those original workers. What's worse, some publishers or producers don't care much about this kind of reproduction or copy as long as they can get profit from the selling. That's because they know it's not an easy job to win the case in China if you sue them. Copyright of books or songs is hard to be protected.