He compares the life of a farmed animal to a worker who has to fight traffic to spend their time working in a cubicle, but an office worker has leisure time, probably a family to spend time with, and enough money to make them willing to work at the job in the first place.

Also: very few office workers get mutilated to prevent them from mutilating their coworkers out of stress, or locked into their cubicles full-time and forced to wallow in their own faeces (periodically being hosed down from outside), or are so over-bred for meat production purposes that even in their cramped conditions the strain of their under-used, oversized muscles strains their skeletons and joints to the breaking point.

Oh, and instead of a salary designed to seem big but actually undervalue your performance, you get paid in being killed (not infrequently a painful and lingering experience) and having any children you bore taken away for no obvious reason.