Such inconsistencies are not rude. (a concern the OP raised in the original form of the question)
Movies and books are different media, and one cannot adapt a work from one medium to the other without performing a large degree of interpretation. Some directors attempt to minimize interpretation (in my own estimation producing inferior and soulless derivative works... 862
but that's just me, and some folks love such films for the very same reason :), while other directors embrace interpretation (for me, <PERSON> Harry Potter and the Prisoner of Azkaban was the best of the <PERSON> films, because he was the director most embracing of interpretation, but some folks hate it for the very same reason). This can even happen in books that reinterpret books—that is where the works are both in the same medium—such as Harry Potter and the Methods of Rationality (<PERSON> reinterpretation of <PERSON>'s series), The Last Ringbearer (<PERSON> reinterpretation of <PERSON>'s Lord of the Rings), and Wicked: The Life and Times of the Wicked Witch of the West (<PERSON> reinterpretation of <PERSON> The Wizard of Oz), each of which are serious literary reinterpretations of works by other authors, and all of which were written out of genuine interest in and respect for the work of the original authors… even when written as criticisms.
You might be interested in the literary theory the death of the author, which more or less argues that an audience has agency in interpreting the meaning of a cultural artifact (like a text). Because film directors and screenwriters who adapt a book to the screen are both audience to the original work, and author of the reinterpreted work, the experience of a movie viewer may involve the figurative death of two authors: the original author, and the director and/or screenwriter.
Back to my opening assertion: such inconsistencies between books and movies are not rude, because a director or screenwriter has no moral or ethical obligation to follow the specific vision of the original author, and must necessarily interpret the work. Of course, the filmmaker may fail, may be incompetent, or may be brilliant in their own interpretation, and that is for their audience—including you—to judge. 460