Good newspapers often attribute (either in the byline or in a footnote) when files from other sources have been used. This is a useful piece of information for the news consumer, and it is even possible, if one has a sharp eye, to discern what the file material is likely to be.
However this is a practice rarely used in broadcasting or in online journalism. According to the Law of Delegated Trust, the publisher of material gathered from trustworthy proprietary sources (such as CP, AP, UPI, Reuters, ITV, etc.) assumes that all material thus received has previously been certified as accurate according to accepted journalistic practices.
In no case that I am aware of except for those rare times when a news syndication service has transmitted an egregious error do news organizations routinely explain the way this works to their consumers.
The consumer has no idea that this law exists. There is no rule of disclosure that is accepted industry-wide. There is no label on news products to inform the consumer of the ingredients.
When there is no system to inform or disclose accepted but hidden news practices to consumers, the news practices themselves suffer, and the risk of a catastrophic meltdown of trust becomes inevitable.
With the increasing dependence on digital networks for the collection and distribution of news products, the industry must develop a way to certify their output, in the same way that many other industries are doing.
