I understand your point (and agree with it), but who would own them if not corporations? A hippy commune?
(and there are at least 2 TV news sources, the only 2 I ever watch, that are owned by governments....so I suppose that's an option as well)
Something like the BBC, if properly implemented, would be great, but I really don't trust the US government to manage something like that appropriately (on a related note, though, I do love some NPR).
The problem I have with the ownership of the news channels isn't that they're corporate entities, it's that they're all, in some form or another, just subsidiaries of various giant media/entertainment/electronics conglomerates. I wouldn't have an issue if they were managed by independent companies or whatever, like they used to be. CNN being the cable news component of Turner Broadcasting, for example, was completely fine. But when they're owned by a company that also owns amusement parks, sports teams, record labels, video game developers, internet service providers, movie studios, publishing companies, etc etc etc... things start carrying a bit of a burden of suspicion.