There is lots of information on the history of media in the U.S. Read up on that muckrackery history I mentioned. William Randolph Hurst, etc. Google it. In America, the news was originally a side-activity of printing and other companies, etc. Just as when radio and TV started the news was a public service add on. In the case of using public airwaves, it was a regulation.

Big industrial change takes a decade. CNN's planning, organization, and early work was far before it's founding date and out of the effects of the changes going on in the 70s.