The question is why is this story not covered by the Washington Post?

The answer involves the degree of editorial indepence they have and sheds light on the precise the motiviations of the world's richest man for buying a masthead newspaper.

Different people will draw different conclusions. I suspect there will be a majority leaning in one direction.

Do you think NYT's article is inaccurate in some way?

You can be biased without being inaccurate.

You can also be biased without it being a bad thing.

I am biased towards hot chocolate and duvet nests and against TV programs presented by people with sunglasses on the top of their head. Am I a monster?

I think they do a poor job of considering more than one viewpoint on some issues. Even on issues that only have one correct answer, I expect nominally neutral outlets to help me understand the thought process driving the people I disagree with, instead of being forced to conjure strawmen

That's conspiracy thinking. The NYT covers a lot of negative stuff about a lot of prominent companies because it's interesting to readers. You haven't even demonstrated that Amazon gets coverage out of proportion to its scale [1], let alone that it's unduly negative. And if you did, you still wouldn't have any evidence that it's part of some sort of high-level conspiracy.

[1] Which is huge; they're #5 on the Fortune 500 and employ 647,000 people: https://fortune.com/fortune500/2019/amazon-com