Obviously that last untested theory "If the news industry is a competitive market" is wrong.The news industry is competitive only in ways which do not cut the revenue of journalism as a whole. It's perfectly fair, in that world, to try to deliver the news faster than anyone else - what is considered unethical is to select the news on the basis of what is important and true rather than on the basis of what will sell the most papers.
Ironically, what sells the most papers is reports which call the safety of the reader into question. Which, IOW, implicitly make the case that the reader would be a helpless babe in the woods if not for the fearless reporter protecting him from otherwise unsuspected dangers. Such stories are inherently anti conservative, but the conservative public as well as the liberal public can't pass by the newsstand without reading that kind of story, even as he dissects it and ultimately dismisses it.
Do the major media outlets in the U.S. have a liberal bias? Few questions evoke stronger opinions, and we cannot think of a more important question to which objective statistical techniques can lend their service. So far, the debate has largely been one of anecdotes ("How can CBS News be balanced when it calls Steve Forbes tax plan wacky?") and untested theories ("If the news industry is a competitive market, then how can media outlets be systematically biased?").The newspaper industry is a system of very limited competition for the simple reason that its members are associated.They are members of the Associated Press, in fact - and that produces the system in which all claim that all are objective.
And that leads directly to their inability to see that their own incentive to hype their own importance - which motivates story selection and emphasis in very standardized, formulaic ways (Man Bites Dog, not Dog Bites Man; If it bleeds it leads, and so forth) - is a powerful leftist bias shared by all commercial, mass-market journalism.