Not in the slightest bit natural, in nature grass fields are a very short lived occurrence, filling with trees and shrubs within a year or two. There are places where it does thrive, places with extremely cold winters that are, wind swept, semi-rocky terrain and such, but those are not heavily populated in most of North America for obvious reasons. The obsession with lawns western culture has created over the last 120 years or so is so wasteful and utterly useless. Good for business though, and creates hundreds of thousands of jobs, so there is that.
Of course it also leads to hundreds of thousands of tons of green house gas from lawn mowers, weed eaters, detachers, aerators (all horribly inefficient motors) not to mention what the seed collection industry creates.