The Nixon-Frost interviews, far and away the best piece of journalism to pop before our eyes on the TV screen in a very long time, couldn't get on any of the networks. Nevertheless, the segments have commanded large viewing audiences and been so newsworthy that the networks have been but in the embarrassing position of having to report on the very same material that they had refused to put on the air.

As extended interviews there probably has been nothing like Frost's performance sice the CBS-Edward R. Morrow interviews of a generation ago. Perfectly prepared, nicely srticulate, Frost not only asked the right question the right way at the right time, but, and this is rare among television magpie newsperformers, knew when to shut up and listen. You would think then, that CBS with its traditions would have bought the Nixon-Frost programs.

Richard Salant, president of CBS News, was given the chance to buy, but he didn't. When asked about that by Mike Wallace on CBS' 60 Minutes, Frost had this to say:

"He (Salant) felt that he could not break this rule - that all CBS News is wholly produced by CBS News. I don't feel like mounting a crusade on this point but I do think sometimes the thought that there are only three men who can put serious news on American television - unless you erect your own network - maybe is not the diversity of broadcasting we would like to see in America."

In answer, the program had Salant saying, "It's a valid point and it's a close question . . . Are we supposed to take responsibility for things in the hard-news area or the current issue area where we have no control and no responsibility, no idea of how it's built up? That's our responsibility; just as The New York Times isn't going to turn over its first page to outsiders, in general, we can't either."

The Times may not turn over its front page, but it regularly publishes opinion pieces by people who don't work for the paper on its op-ed page and, this is more to the point, it routinely buys everything from news stories to feature articles in its magazine from journalists and others who aren't on its staff.

If The Times considers it necessary and desirable to contract for a great variety of journalist services outside its shop, how come the three networks, which combined have fewer reporters than that one newspaper, take the position they can only maintain the high standards of their product by producing every foot of news footage themselves. Even if we concede their standards are as high as network executives say they are, people like Salant miss the objection Frost is raising.

Should three corporations have this much power in what is in effect a government-created monopoly? The networds say yes because they say by exercising that control the chances are better that they will get any given news story straight while others may not.

That presumes that there is a single unique way of getting a news story. But any depiction of a news story is only one version of the event - in the case of television, the version these three corporations, with their government-given advantages and protections, choose to show. What people are clamoring for are other versions, other ways of doing things, of depicting them and displaying them such as David Frost's simply super interrogations of Nixon.

What's more, the national network news, flawed and monochromatic as it is, doesn't show how lightly these people take that sense of "responsibility" they talk about. For a more accurate picture, look at what the networks do with the news on the local television stations they own.

Here are three examples drawn by Ron Powers, an NBC employee at WMAQ-TV Chicago, in an article entitled "Eyewitless News" (Columbia Journalism Review for May-June).

The ABC-owned Chicago station WLS showed its weatherman by a North Dakota highway holding up an envelope while he asked, "In this envelope are a group of never-before-published pictures of flying saucers. Are these things real?" KNXT, CBS' Los Angeles station, showed a female reporter in a wet suit going into a tank of water to play with a porpoise. WKYC, NBC's station in Cleveland, set reporter Del Donahue into a lion's cage where the poor man was mauled by the neast and needed 60 stitches to be put back together again.

Network news is veering in the same direction. The other day, NBC had Irving R. Levine, a man who has served the trade long and well enough to deserve better, posing with a drink and cigar on the presidential yacht Sequoia in order to illustrate the eyewitless news point that most of us couldn't afford the yacht even if it was up for sale.

Wilder stuff may be coming since Roone Arledge, the impresario of ABC Sports, has taken over ABC News. In nervous anticipation of the competition, NBC has announced plans to improve its Chancellor-Brinkley show by installing a new set and generally gussying things up. Perhaps the next time you turn on the news, you'll see Roger Mudd wrestling a bear.