When good people do bad things
The main idea that best describes a central idea of the text

desperation

Explanation:

good people only do bad things by accident, or out of desperation

American railroads were created to serve regions limited to the municipalities and their contours. Thus, the technical aspects were chosen in each state according to the preference of the engineers.

As the country's development progressed, markets expanded and locomotives had to move beyond their limits. Thus, a standard was agreed and all tracks were standardized.

Thus, trains of different railway lines could use the lanes of each other, according to item C of the question.