The author includes Lori Zara's opinion of Chris as a McDonald's employee to show that Chris thinks and behaves differently from others.
The most likely reason for including Lori Zara's opinion of Chris as a McDonald's employee in paragraph 3 of page 40 is to show that Chris thinks and behaves differently than other people.
This can be inferred from the passage where it mentions that the book, 'My Secret Life on the McJob,' documents the experiences of an undercover fast-food worker. The author's inclusion of Zara's opinion helps illustrate the diverse perspectives and experiences of the employees.
By including Chris's unique behavior and mindset, the author highlights the individuality of workers in the fast-food industry and challenges stereotypes or preconceived notions about them.