Runners perform more tasks than just piloting. They are leaizons between other members of the crew and the ship's AI. Although other crew members can talk to the AI, runners interact more intimately and more immediately. They share consciousness.
Runners also have to perform a lot of other ship duties if they are the only crew on a smaller ship: they interface with maintenance, inspectors, space station personel, shippers, buyers, sellers. They may need to negotiate or make decisions for the shipping company or individual owner.
Star, being at the top of its class, was selected for government duty, especially military duty. This was a poor decision. The discipline and narrowness of the position frustrated STar and STar did not flourish. The Institute chose to make Star surplus rather than to try to retrain STar for a currier position. They couldn't imagine STar working for a shipping company after having been exposed to the technological wonders of a starship. Their lack of imagination almost cost STar its life, but STar had enough gumption to get the training it needed. It paid for the training by working for a company until the debt was paid. Then STar went out on its own, finding a backer and then going solo.
