If you look at "content with the most shares" not surprisingly Reuters and Patch tops the list.
OP's headline presumes any algorithm should achieve left/right balance - this is just impossible.
There was a good tweet the other day something along the lines of
If I Google a headline the results are:
* New York Times: Your number of free articles is 0
* Wall Street Journal: Subscription needed
* Bloomberg: See this article for $1
* Fox News: Completely free
* Breitbart: Completely free
Seeing this its no stretch to understand why media struggles