John Yui was once a so-called wandering martial artist. Wandering Martial artist is the term used for any martial artist that doesn't come from any of the established clans. His original name was John Dunphy, he had married into a very influential martial arts family and took his wife's last name.
Even though Martial Artists weren't as influential as they once were, they were still a class above the normal citizens. Even in the military, most high-ranking personnel were high leveled martial artists. Though there were some non martial artists that have ranks, the most they can achieve was becoming a first lieutenant, since the requirement for going above that rank was that you need to be at least a rank seven martial artist or have the strength of one. At that point, non martial artists would need to enhance their bodies by replacing their biological body parts with mechanical ones.