Interviewed through a contract agency. First was a thorough phone screen and resume review. Then came a discussion with the account manager on behalf of the Amazon hiring manager.
Through a series of questions, the account manager learned for how long I've been an engineer. He said (paraphrasing) "the hiring manager is interested only in persons no more than 5-10 years in the industry because younger people are more interested in learning". Then the interview process abruptly ended.
Age discrimination is real, even at Amazon.