The author should explain how Rapunzel's story fits into the thesis.
He starts his thesis by saying the the Grimms' fairy tales address the experiences of people who are living in difficult situations. The next logical step would be to give examples explaining and supporting his original statement. He mentions the story of Rapunzel but does not explain how the story supports his statement. When writing a thesis you cannot just assume that the readers know everything that you are talking about, you need to give explanations. He needs to explain how Rapunzel's story fits into the thesis and supports his initial statement.
He could also do with explaining the story of Hansel and Gretel in more detail really but initially he needs to explain Rapunzel's story.