Maybe the adversarial evaluation process has a poisonous effect?
(I don’t know that this is the case with Amazon: I’m just providing an anecdote based on my observations at places I’ve worked.)
May be because their performance review prioritizes employee contributions that impact bottom line immediately instead of building infra that might improve developer productivity?
There was a clear culture shock for some of the more seasoned Amazonians (and you could see a fall out effect with some "mails to your manager" every now and then if you crossed a Grand Poobah the wrong way), but to all of us "newer" hires, the times of adversarial review were just a story.
Anecdotally, I can say with confidence that some teams have a lot of autonomy in deciding to follow (or not follow) company-wide practices / guidance like what you've posted (obviously, only a few do it, since non-compliance isn't officially blessed). I was lucky enough to work in a team which was much better than baseline. But I try not to let that colour my memory - I heard and saw plenty of horror stories, and I saw plenty of people (including in my leadership) trying to do the right thing. Like most things, there are shades of grey here.