https://en.wikipedia.org/wiki/Native_American_use_of_fire
Because native never used fire to alter the environment....
Quote:
[ Romantic and primitivist writers such as William Henry Hudson, Longfellow, Francis Parkman, and Thoreau were major contributers to the myth of pristine pre-columbian landscapes, which became part of American heritage.[4]
At the time of their writings, however, enormous tracts of land had already been allowed to succeed to climax thanks to the reduction in anthropogenic fires caused by the collapse of aborigeneal populations brought about by epidemics of diseases introduced by Europeans in the sixteenth century.
Influenced by Western noble savage views of hunter-gatherer societies, many people still believe that Native Americans lived in complete harmony with the environment and neither disturbed nor destroyed but took only what was absolutely needed for survival. One of the powerful technologies which Native Americans had was fire, and they clearly changed the landscape with it.
Sometimes to clear the woods for hunting or travel, sometimes to create a berry patch, the changes could be found in patches across the continents.}
Volcanoes never used fire to alter the environment either, did they. They’re just innocuous holes in the ground and stuff.