Why Was the Hollywood Version of the Western "Cowboy" Based

Why was the Hollywood version of the western "cowboy" based more on fantasy than reality?

A) Railroad expansion before the Civil War had eliminated the need for "cattle drives" from Texas.
B) Most cowboys were low-paid workers, some of whom even went on strike for higher wages.
C) By the time of the Civil War, most open-range longhorns had been decimated by disease and harsh winters.
D) Clothing such as wide-brimmed hats and boots were twentieth-century inventions of writers and movie producers.
E) Many worked as cowboys for a short time before moving on to other employment.