Looking back over the NYT article — it was balanced. It had quotes from both sides, and whole slabs of text about how Amazon can be a good place to work.
But — and this is a skill of a (good?) journalist — all that balance is overshadowed by the impression of the article, which is that Amazon sucks.
Very few among us want to read an article that *actually* gives equal weight to both sides. Journos observe the letter of the law with respect to balance, but give the readers what they want, which is a story that, in the reader’s memory, has a clear message.