Amazon Software Engineer interview questions

I had 6 hour interview with six people. Everybody was friendly and professional. Within a week they informed me about their negative decision and asked me to provide a feedback about how they can improve their interview process. I did provide them feedback with suggestions and asked them to provide me with feedback about how I can improve since I was having interviews with other companies. They refused. After that I got two emails asking to fill their interview survey. Well, that's probably how they understand reciprocity.