Which is NOT a contributing factor in the higher efficiency of trucks over rail?

Trucks inherently offer higher efficiency in various scenarios primarily because of their operational flexibility. The choice that identifies a non-contributing factor is cost, which doesn't directly relate to the unique efficiencies provided by truck transport.

While trucks can often be less expensive for certain routes and loads, efficiency is more about the practical aspects of their operation rather than just cost savings. Trucks excel in their capability for easier pick-up and delivery, ensuring they reach locations where rail systems may not be present. This door-to-door delivery capability allows for a seamless transportation experience that rail cannot provide, as it typically requires additional steps to transfer cargo to trucks for local distribution. Moreover, trucks offer the advantage of regular delivery schedules that align better with consumers' and businesses' needs for timely transportation.

Thus, the primary efficiencies associated with trucks revolve around their operational advantages, not strictly cost, which can vary greatly depending on various factors in logistics.