Not giving details on HN but happy to send a bunch of email proving this if you're from a noteworthy publication.
The copy that a business would send us rarely made air. I know, because I was often the person who rewrote it.
Example: At a talk radio station I worked at a number of years ago, we received a press release from a person who was protesting John McCain's policies in a very particular way. It was very positive, and spoke of his mission, and blah blah blah. We had no clue who this guy was, but it tipped us off to a great story; we didn't cover it in the news portion of our broadcast, but the talking heads that evening had a very good time pointing out how ridiculous it was.
This is how news works. PR helps a producer by bringing their attention to something, because let's face it, omniscience is not a trait of local news producers. The producer might help PR with a bit of coverage, or very likely doesn't. (The fax machine at a local newsroom is hilarious to watch.) The angle that gets covered is occasionally not what PR wants. This relationship is push and pull.
However, having pre-written copy introduces vast amounts of bias by shifting how people are thinking about an issue. Thus, you can't rewrite it without first being influenced to think along similar lines. Now, one option is a simple firewall that prevents the person writing the story from reading original copy. More effort in the short term, but companies would have less incentive to try and shape the news for free press.
PS: Really, pink elephants, now where you thinking about elephants or did I suddenly change your thought process... It is possible to minimize bias, but failing to take obvious steps suggests they are not even trying.
As a PR I was initially astonished that my releases would be duplicated verbatim by journalists - and yet it happened, so I was clearly doing both my job and helping them out.
Sorry, I'm not clear what you are suggesting is unethical.
As a journalist, I loved PRs who sent me interesting stories pitched at my interests and publication. Yes please - send them in. That didn't mean that I didn;t then do my job; speak to competitors, treat the pitch with a fair degree of scepticism, etc.
What's being described in the article is quite different - deliberate corruption of the editorial process.