I can’t remember the last time I watched TV2 but unless it has changed there is nothing on it to justify public ownership.The problems Homepaddock has with "public ownership" of the television stations may well come down to the point that the "public" don't own them, the politicians do, and so they respond to the wishes of the politicians not the public. There is no accountability to the taxpayer, which I'm guessing is basically Homepaddock's point.
TV1 has a few programmes which might not appear on privately owned stations, but like Agenda, for instance, they mostly screen at times few people find convenient to watch them.
There may be a case for public service television but TVNZ doesn’t provide much evidence for it.
The question is, Why is there no accountability to the public? The short answer is because the public don't own the assets in the first place.
The important point here is that without control you don’t have ownership. As Oliver Wendell Holmes Jr. put it,
But what are the rights of ownership? They are substantially the same as those incident to possession. Within the limits prescribed by policy, the owner is allowed to exercise his natural powers over the subject-matter uninterfered with, and is more or less protected in excluding other people from such interference. The owner is allowed to exclude all, and is accountable to no one. (The Common Law, p193, (1963 edn.))Clearly the “public” does not have the rights Holmes refers to. The government has these rights. Following Grossman and Hart ("The Costs and Benefits of Ownership: A Theory of Vertical and Lateral Integration", 'Journal of Political Economy', 94:691-719) economists tend to define the owner of an asset as the one who has residual rights of control over the asset; that is whoever can determine what is done with the asset, how it is used, by whom it is used, when they can use it etc; the public can do none of these thing with a public asset. Hence the public doesn’t have ownership.
The public have no ownership and thus there is no accountability to them.