When you look at the Dime Novels and newspapers of the era, every revolver was a Colt and every lever action was a Winchester - those terms covered the gamut, insofar as the articles were concerned.
The term 'bowie knife' fell into the same category - even at a time when most side knives were butcher knives of some type - it read well.
When the Rough Riders were equipped, the Army did issue the Model 1880 Hunting Knife, and those sometimes show up in period photography, but when compared to a readily available butcher knife, their utility was suspect.
Remember too, that that TV show has zero basis in reality.
Scouts Out!