The USA, like almost all countries, licenses parts of the radio spectrum for domestic use, and it reserved chunks for television, satellites, cellular telephones, digital radio and the like. Since the 1950s, broadcasters have been able to trade licences, thus establishing that licences are valuable property. The Commerce Department had blocked the release of 200 megahertz of bandwidth, estimated to be worth $10 billion in 1991. It was planning to either give away rights to bandwidths, by assignment on the basis of deservingness or lottery, or to auction licences to the highest bidder.
Private ownership of airwave bands prevents deserving newcomers offering new services in the future. By selling off the airwaves the government is prevented from fulfilling its primary duty, of ensuring that the airwaves are reserved for the uses that are in the public interest.
The airwaves are free for all users. The government cannot sell what is does not own.