When it comes to topics like this, I think the best that the authors of books can give you is an overview, an explanation of the principles, the
patterns of behavior and organization that are helpful, anti-patterns, and other things of a more abstract and high-level nature. It's really up to the reader to find ways to take those high-level concepts and apply them to specific situations. Since there are so many different ways these ideas and frameworks can be applied, I don't think it's realistic or fair to expect the author's work to apply to every readers' situation. If anything, a brief overview of some case studies might be helpful but I see those as nice bonuses rather than required material. It's great if the book has them but I wouldn't necessarily count it against the author(s) if they didn't include any.
Take for example the practice of co-located teams and constantly available users. That's a highly recommended practice for XP and Scrum. However, there are some companies where having co-located teams and users who are always available is just not a realistic expectation. In those cases, you really should go back to the principles/values, which is rapid feedback and constant collaboration. Given that, you have to adapt different processes and practices so that you can still stick to the principles without necessarily following the recommended practice. It's up to the
reader to take what the authors write and see if/how it applies in their specific contexts.