If there were a per-story bias, or even a per-author bias, I might agree with you, but NPR has a very clear per-topic bias. And the goal of every reporter should be to eliminate their personal bias and report the facts. NPR's bias is so pervasive on certain topics though that one can only conclude that they too are taking dictation from some overlord, or are so caught up in group-think that they have fundamentally misunderstood reality.
I don't actually think this is too bad, as long as you know what you're getting and can correct for the bias.
Consider the most recent geopolitical conflict involving the US, the war in Ukraine. There are a number of articles on NPR's website about the possibility of the US sending F-16 jets to Ukraine.
I've read many of them, and they tend to support the US sending planes. Some of these articles include quotes from Ukrainian defense officials who are obviously in favor. Some articles speculate as to why the US has not done so (e.g. the overhead of training pilots).
My issue with the reporting is that the writers never really bothered to explain the arguments from the opposing side. Obviously, this decision involves many tradeoffs and it was not taken lightly. NPR's reporting on this subject was not very informative and it just left me asking more questions. As a reader, I want to understand the tradeoffs behind important decisions.
This isn't the only topic with shoddy reporting. It's just the first one I noticed where activism got in the way of journalism. There are legitimate arguments in support of both sides of this issue (and I say this as a supporter of Ukraine). Readers are entitled to read/hear them, and writers should present them fairly.