Writers for media (I hesitate to call them “journalists”) have no incentive to find facts. They have an incentive to craft a story, based on whatever information they already have in front of them. If they already have most of a story, and a cursory search turns up no obviously interesting facts which add to the existing story, they’ll leave it there. There is simply no reason to go digging.

It’s only where there’s no story without digging, and/or where the more you dig the more story you get, when you get investigative journalism.