How might they enforce? Using the media to barrage the public about the “dangers” of “unauthorized” drone use, encouraging the public to report people seen flying drones to local law enforcement, is a distinct possibility.
The feds and corporate aerospace has already done s great hob of demonizing private drone use while praising corporate/government drone ops in the next breath. The general public is just too stupid to recognize the only people getting killed by drones are being killed with government drones made by the same outfits that will be operating in civilian airspace.
Recreational drones are not the bad guy but they are being vilified as a means to promoting government and large corporate interests. Delivery of packages is not even close to what all this stuff is about. The real goal is to incorporate drones in civilian airspace to keep better track of you through multiple agencies.
Power and control, with personal information used to obtain more power and control.