The media likes patterns until the novelty wears off. Remember when carjackings were the "in thing" to report? Now they don't make a peep unless a child is taken with the car. Remember when shark attacks were the in thing? When's the last time you heard about one of those, and I'm sure they are still happening. Reporting on police pursuits? Hot then gone. Dangerous toys from China. E.Coli at a particular restaurant chain. All had their run then *poof*. Someone in the news room will take an interest in, say, boating accidents and you'll get a run of serious injuries from Louisville to Lithuania to get enough to make a pattern, then it'll just drop.
It's like a formula. Take a remote risk. Run with a bunch of isolated examples to make it seem more relevant and scary to the viewer/reader/listener (thus more interesting, thus more viewers), but then drop it when the novelty wears off. You can only cry wolf so many times, after all, and when the wolf is always after someone else's sheep folks start to lose interest. Maybe you can spin it into a human interest piece for awhile, get some clowns or controversy to keep the margins interesting for awhile, but eventually they always move on to the new hot thing. Is tap water killing your children? Is this common household chemical causing your property values to plummet?
Yeah but "gun violence" is a hardy perennial...especially when it can be weaponized (pun intended ) to enact more gun control. Of course the best ones check off certain boxes deemed to be most useful.