Ex-Amazonian, not in a software related position. I left for the same reason a lot of the fellow commenter did, internal politics, promotion / development and shitty bosses (two levels up, but that's where it counts).
For one, as great as Amazons Leadership Principles are in theory, in practice they are used more than a weapon than anything else. Once the higher ups have made up their mind about a person, no amount of feed-back will change that. In the end perf reviews resemble court-martial, except in a decent court-martial you are present to defend your self.
I realized that too late. Internal "voting rings" self-promoting members at the expense of other are aggravating this even further. I would still do it again though, only with a clear exit strategy from day one. Rough guideline, if you failed to get promoted or transfer internally by year 2 - 3 you are by default dead. A transfer buys you another 2 odd years of runway.
What did definitely not help was stock development. I joined in early 2014, initial RSUs have beem granted nased on 2013 expectations, the value increased by a factor of 10 by now. So AMZN had yet another incentive to reduce the number of employees in my generation of hires. And they did.
Funny side note, around two years after I left they implemented tje two high level solutions I proposed back the day and got axed for.
Since then I had two employers which didn't work out. Mental note: take the sabbatical immediately after leaving, failed to get start-up ofbthe ground and finished my studies.