People often equate "Public" with meaning "middle-center" or "apolitical". Many would claim National Public Radio (NPR) is middle-center, politically-speaking.
Plenty of people disagree with that statement, and those who agree tend to like NPR's messaging - hence the "bubble" you referred to. Good, non-partisan reporting should make "both sides" groan from time to time.
If you find yourself in agreement with nearly everything said, then it's a fair sign the politics lean "your direction".
that's a mischaracterization of what neutral or apolitical is.
The broadcaster doesnt have to report that killing puppies is good once in a while!
I'm confident you understand the difference between killing puppies and the bias, partisan reporting that occurs on many "news" stations.