Amazon.com said last year that its delivery drones would be ready to be deployed as soon as federal regulators allow them.
A report in The Wall Street Journal, however, said that isn't likely to take place until the next decade.
The paper reports that commercial delivery drones will need sophisticated systems that rely on sensors both on the ground and in the air to avoid mid-air collisions.
Not only do such systems have yet to be developed, but regulators only recently began discussions of how the delivery drones will be regulated.
Drafts of those standards are not expected to be completed for three to four years, and the Journal noted that the Federal Aviation Administration currently has different drone-related regulations farther up its list of priorities.
The FAA authorized small commercial drones for limited, routine uses earlier this year, and the agency will reportedly next take up rules to expand those uses and enable inspections via drone by railroads, pipeline companies and other operators with safety implications.
Only after those wrap up is the FAA expected to consider rules allowing drones to fly thousands of feet in the air for commercial purposes.
Amazon and other retail and parcel companies, meanwhile, continue to develop drone technology and, the Journal notes, lobby lawmakers to accelerate the rule-making process.