But this is not really so. Consider the SpanishAmericanWar?, for example. The demonization of marijuana in the UnitedStates? is largely a consequence of WilliamRandolphHearst?'s timber interests (in that way he was able to radically reduce hemp production, the competing source of paper).
YellowJournalism? is a very old thing. But this sentiment is widespread, and captures something of the truth. What might that be?
Around the middle of the 20th Century, journalists began to be more highly educated. For the first time, most were college graduates. There were strong motives for characterizing journalism as a profession, serving the public interest, in the way that medicine and law are supposed to be. Before this point, journalism was a way to sell paper with little black marks on it.
This transformation produced the "watchdog" model of journalism, where journalists are guardians of liberty for the benefit of all. Many good things have come out of this transformation. Why did owners of journalism channels go along though, since it would seem to have been contrary to their interests? For one thing, they were themselves interested in increasing their social respectability. But also there turned out to be a big market for such news. Nothing more, nothing less.
In Europe, things happened differently. Newspapers there usually have quite marked political skews, well known, which color all the print (not just the editorial page). Journalists aren't professionals serving a neutralized version of the public interest, but rather they are information sources and advocates for particular ways of understanding the world.
Back to the UnitedStates?. Professionalism brought with it a code of ethics; the notion that there were things you should and shouldn't do. In some sense, this code of ethics is breaking down, but not as a return to the YellowJournalism? of the past, nor as a switch to the European style. Rather, we have the entertainmentification of all of American life, with the concomitant realization by owners that while NeutralTruth? sells, InfoTainment? sells even better. So the owners no longer care about the ethics, and the money shifts.
And there you have it.