Modern road don't only try to minimize the distance but also other factor like slopes. If you look at old railroads there is a very big constraints on slope and you will see very complex trajectories in hilly places.
Modern railroads typically have extremely tight restraints on slope. This allows trains to be longer and reduces overall shipping costs. In fact, the desire to make railroads less steep has led Americans to do incredible things, like building the Whittier Access Tunnel (and the port of Whittier at all) to avoid trains going uphill coming from Seward.
