Fox came on the scene, and it worked as a business. In the end that means it gets funding, and is the competitive business model.
Other media orgnizations had to deal with all sorts of other barriers such as editorial standards etc.
I will add though, that Fox probably survived competition because it had such a close link to the Republican party. I wonder what would have happend if it were a more active market.
Actually scratch that - I remembered the issue with this market. Once we started having conglomerates of a certain size, acquisitions and the consolidation of media assets and newspapers was inveitable.
So even if there were other conservative view points, it would eventually be absorbed by "Fox" or whatever dominant entity in the market.
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I would like to blame Rupert Murdoch, but I am beginning to see that the man just found a chink in the armor of how society organized its media systems, and exploited it.