I find this an interesting question as well. I am a senior Googler and my old friend is similarly senior at Amazon. He told me that Amazon culture is much more transactional: you're hired to do a job, you do the job for pay and the company discards you when they're done. The company is not your friend. (As I've worded it I make it sound cruel, but in his framing of it, it's an honest but direct relationship.)

In contrast, historically Google culture has tried to be more of a "family", with a lot of talk about perks and culture and a focus on the mission or whatever. To be clear, I don't believe Google has necessarily succeeded in these goals. But rather, that is the employee relationship Google has attempted to represent, so when Google fails at it the employees are more disappointed than when Amazon (you can substitute other employers here, e.g. Oracle) fails in the same way.

Google encouraged political discussions as part of their "bring your whole self to work" policy. Most other companies don't.

Because they cave into the demands for better or for worse.