I think that Steinbeck uses the bus driver as one of the first discussion points between George and Lennie to highlight the naturalist condition in which they both live. The discussion regarding the bus driver, especially in George's mind, represents the challenges that both men are up against in the condition in which they both live. The bus driver dropped them off farther away from the ranch in order to make his own life easier and make theirs more difficult. In making the first topic of conversation the bus driver, Steinbeck is authentically creating the characterizations of the two man, especially George, as individuals who must struggle and toil in a world where suffering is inevitable. The first topic is not about freedom, hope, or a sense of progress. These are not elements that so easily experienced and so readily faced in the world that George and Lennie inhabit. Instead, both men are subjected to the whims of others and constantly find themselves having to be taken advantage of by others. It is in this light that Steinbeck ensures that the first topic of conversation is this very reality, in order to develop the characterizations of both men.