The average journalist has to churn enough stories that they don't have time to be looking up anything. There must be a corollary somewhere about how much you should read the average newspaper.
Also, if any news orgs are listening: when you are regurgitating a press release about, say, a report or scientific paper, please make it your house style to hyperlink to the report or paper. That way I can see your sources and judge the claims for myself.
Also, people who write reports or papers and then make press releases: please upload them to your own damn websites, and make them easily findable by the public. Don't just email the press release to your pals in the media, and not put your words anywhere else.