That's a hilariously naive view of judges. Judges totally have emotional and political motivations, and a huge amount of discretion. It's less "following a rule book" and more "trying to squeeze this scenario to fit the box I think it belongs in". If you think adjudication is anything like running a computer program you're dead wrong.

One of my favorite lines about judges is: "it's the responsibility of every person to know the law, except trial judges, who simply have to consider the arguments presented and have appellate courts to set them straight"