Cleaning up the leaves in a suburban lawn is rarely enforced or legislated. It is just an expected task for the suburban homeowner: thou shall not have many (or any) leaves in your lawn by the end of the fall season. Why is this the case? Here are a few possible reasons:
Clearing leaves is an unquestioned social norm that simply continues on because people did it before. That leaves could be beneficial for lawns and garden beds may not matter; the inertia is already there for clearing leaves and it could take time for new patterns to emerge.
There are commercial and industrial forces invested in making sure lawns are seeded, treated, and cleared. There are rakes and leaf blowers to sell. It is big business helping Americans remove leaves.
Suburbanites pass along this social norm to each other through conversation and exhibited behavior. Neighbors share words while outside about their lawns. One suburbanite rakes their leaves because they see their neighbors doing it.
Perhaps this practice will pass into history at some point. But, as long as we have a suburban emphasis on single-family homes and their lawns, there will be more years of raking, bagging, mulching, and clearing leaves.
Within the next month or so in the Chicago region, leaves will fall at varying rates and cover lawns. These could be leaves from trees in that yard or, given occasional high winds, leaves from several houses away. They could be wet or dry, big or small, green, red, orange, or other shades. And Americans will spend countless hours trying to corral them all, stuff them in bags or bins, and ship them somewhere else.
Why? Because even in the fall, a season that can be good for growing grass, the sanctity of the lawn must be upheld. Even as trees and bushes grow sparse and the flowers that once adorned the property wither, the well-kept lawn is important. Rakes must be employed. Blowers can be even better (at least when the leaves are drier) to efficiently move large amounts. Mowers can be used not only to keep that grass looking uniform but to mulch leaves.
And the best fall lawns, the ones showing the suburbanites of a higher social class or those who care the most about their property (values), will have no visible leaves. They are a blemish and may be removed daily. Carpets of leaves may be pretty in more natural settings but not on the suburban lawn: it must continue to show off the home and its owner until either covered by snow or gone dormant for the winter.