In chapter two

Both the Diners and the Oklahoma City Transport Company truck is both imposing and intrusive, a symbol of pervasive corporate influence (as shown by the "No Riders" sticker that is so prominently displayed). Tom Joad immediately voices the idea that business is cold and heartless when he asks the truck driver for a ride. Overall, The Grapes of Wrath is unsparingly critical of business and the rich: these groups, here, serve only to keep truck drivers isolated and bored to the point of near insanity.