Between 1949 and 1987, US private companies were forced to pay for and produce high quality news content under guidelines set by the federal government.
One of the conditions of ABC, CBS and NBC being given access to the airwaves was that they had to produce and distribute high quality news broadcasts. News was considered a public good.
From wikipedia:
The fairness doctrine had two basic elements: It required broadcasters to devote some of their airtime to discussing controversial matters of public interest, and to air contrasting views regarding those matters. Stations were given wide latitude as to how to provide contrasting views: It could be done through news segments, public affairs shows, or editorials. The doctrine did not require equal time for opposing views but required that contrasting viewpoints be presented. The demise of this FCC rule has been cited as a contributing factor in the rising level of party polarization in the United States.