Two, it's a matter of scale. Facebook reaches a far larger audience and has far more detail into their preferences and can nano-target personalized stories for them and corral them into groups, creating perfect echo chambers. The news companies are way too small and in some way irrelevant. Even if they all went bankrupt overnight, Facebook's algorithms will keep working, keep producing personalized truth bubbles. Is fake news a problem in general? Sure. But the news companies are tiny compared to Facebook, and not the immediate and persistent threat to democracy that Facebook is, just because they're much smaller. Even if you take the entirety of local news networks as a whole, they don't have the same saturation and engagement feedback loops that Facebook has.
The Powers That Be are typically reactionary forces, and has long battled the news industry over free speech and censorship etc. Facebook is a relatively new villain, different than the old ones, and way more powerful. Further regulating the news industry won't really deal the Facebook issue since they can keep on aggregating from anywhere and everywhere. It's a different beast altogether.