Uh, how and why? You don’t think all books are art, do you, or that artists can’t fuck up?
There’s also a distinction being disappointed in them for a non-apology and feeling they should do better (which is what I said), and insisting they *must* apologise. Although generally, ‘I’m entitled to an apology’ is standard, widely accepted phrasing, demonstrating that it is considered people are entitled to an apology in certain circumstances. Refusing to apologise or making a non-apology might well be the entitled behaviour.