Why are the words "public interest, convenience and necessity" so important in the regulation of over$-$the$-$air broadcasting?

These three words $-$ interest, convenience, necessity $-$ are the entire governing principle on which broadcast licenses, for both radio and television, are awarded and renewed by the government.

They are the rules the government must follow in regulating the sale of radio receivers to the public.

They are the rules that govern the manufacturing of both radio producing and radio receiving equipmt nt like radios, televisions, microphones and television cameras.