Chief Joseph on Indian Affairs, William T. Hornaday on the Extermination of the American Bison, Chester A. Arthur on American Indian Policy, Turning Hawk and American Horse on the Wounded Knee Massacre, and Helen Hunt Jackson on a Century of Dishonor (1881)

What type of blind spots, biases, weaknesses, or assumptions might the author have that affects his/her/their argument or objective?
Can you infer any effects or influences the document would have had in its own time?