In chapter 1 of Fast Food Nation: The Dark Side of the All-American Meal, some readers find it counterproductive to the author Schlosser's argument against the fast food industry that he would create such a sympathetic portrait of fast food pioneer Carl Karcher. What is the relevance of providing this background information in formulating an argument?

First, in formulating an argument, it always is beneficial to have an "admittedly" paragraph—or if you writing a book, an admittedly chapter—in which you admit to and accept all the strongest arguments your opponents can make. This is exactly what Schlosser is doing in delving into the story of Carl Karcher. People who know about the fast food industry are likely to bring up the good hearted people like Karcher who were just trying to make a living in the best way they knew how and saw that the automobile culture was here to stay. Schlosser is admitting from the start that good people jumpstarted the fast food industry—it is not these folks he is going after.
By doing so, Schlosser acknowledges that fast food as a concept is not inherently evil or bad. That is not the point he is trying to make. He doesn't want to condemn individual entrepreneurs who pushed fast food in an innocent way. It is not fast food per se that is bad but what has been done to it by big businesses determined to squeeze whatever profit they can out of it, regardless of human costs.

Schlosser paints a sympathetic portrait of Karcher to put the evolution of the fast food industry in context by tracing its history. However, the author warns the reader in the first paragraph that this is a cautionary tale; that is, "a warning about unintended consequences" (paragraph 1).
Karcher and his cohorts, other founders of fast food restaurants, mostly came from poor backgrounds and struggled to make a living working long hours. They all took advantage of the new "car culture" that swept America. Drive-ins with carhops became instantly popular. However, Richard McDonald changed all that with the first self-service restaurant that eliminated the need for carhops, waitresses, and even dishes and silverware. This history of fast food sets the scene for the changing landscape of a fast food nation.
The careful reader of chapter 1, "The Founding Fathers," will pay close attention to this cautionary tale, and the author's last statement when he looks out the window and all he sees are strip malls, fast food restaurants, and subdivisions where tracts of land once flourished with ranches and citrus groves. Schlosser asks Karcher if he misses the old Anaheim. Karcher's reply, "I couldn’t be happier . . . I believe in Progress.” The irony should not be missed that taking the natural landscape and turning it into a cement jungle is considered progress, just as turning America into a fast food nation could be considered progress.

Schlosser provides a somewhat sympathetic portrait of Carl Karcher to highlight the origins of the fast food industry.
Schlosser chooses Karcher to open his work because it demonstrates how the industry began with good intentions. Karcher was a self-made man. He struggled with poverty, worked very hard to achieve his dream, and saw an opportunity in California's changing dynamics to do so. Highlighting Karcher's rise demonstrates how those who started the fast food industry were instrumental in the preparation of its product. For example, Karcher opened the first Carl's Jr. in 1956. Karcher was not only the proprietor of the Carl's Jr. chain of restaurants. He was also a worker. Schlosser details how Karcher would work after hours to perfect his "secret sauce." Karcher was knowledgeable about every aspect of the operation because it was his dream. Schlosser's analysis shows how Karcher studied the patterns of his rivals and sought to integrate similar approaches in his food products. Karcher made decisions that enhanced the financial health and food quality in his restaurants.
Karcher's intimacy with his food products stands in vast contrast to the practices in today's industry. As his work progresses, Schlosser shows how financial gain motivates decisions. Poor food quality and its unsanitary preparation as well as kitchens abounding with rodents and insects are realities of the modern fast food industry. Given how close he was to his food products, Karcher would repudiate such conditions. Schlosser's sympathetic view of Karcher allows us to see how the origins of the industry are vastly different than what it is today. As a result of Schlosser's viewpoint, it is clear that inventors of the industry like Karcher would not stand by what it has become.