While there have been a few comments claiming otherwise, the simple fact is that not all airspace in the US can be regulated by the FAA.
The US Supreme Court ruled in US v Causby in 1946
""We have said that the airspace is a public highway. Yet it is obvious that if the landowner is to have full enjoyment of the land, he must have exclusive control of the immediate reaches of the enveloping atmosphere. Otherwise buildings could not be erected, trees could not be planted, and even fences could not be run. The principle is recognized when the law gives a remedy in case overhanging structures are erected on adjoining land.[9] The landowner owns at least as much of the space above the ground as he can occupy or use in connection with the land. See Hinman v. Pacific Air Transport, 84 F.2d 755. The fact that he does not occupy it in a physical sense — by the erection of buildings and the like — is not material."
The FAA has jurisdiction of the navigable airways, it does not have jurisdiction over YOUR use of the airspace immediately above your backyard and they cannot regulate the use of drones of model aircraft outside the navigable airspace any more than they can require you to get a permit to plant a tree in your backyard.
Now the FAA won't admit it and likes to pretend that they have control of the air around your head, but it is clear from US v Causby that "must have exclusive control of the immediate reaches of the enveloping atmosphere".