Why is it so difficult to cite sources?

Particularly, why is it so difficult for major newspapers to cite and refer to sources properly?

I ran into an example: Both The Guardian (3.8.) and Helsingin Sanomat (11.8.) mention a study by International Energy Association, about subsidies for fossile fuels. But they make absolutely sure not to link to the IEA Web resource. (HS is also a bit slow, but come on, it's barely the end of our holiday season.)

Of course, there is a good answer: if a newspaper would cite sources, it would be too obvious and easy for the readers to see how far the ready-chewed opinion offered by the paper is from the actual facts provided by the source.

This is particularly apparent with The Guardian, whose agenda was shown (in rather aggressive terms) by Tim Worstall. The Guardian article was severely misleading by comparing figures that are very much apples versus oranges.

Hey, wake up. In the Web, it increases your credibility if you link to your sources. Being a big and mighty newspaper won't carry you too far into the future.