Companies like Amazon have standardized procedures for interviews. At the company I work for, the person interviewing isn't going to be the same person who hires you, so they need more data that just the interviewer's notes. Also, deviating from the standard procedure opens up the effect of unconscious bias.
This is the correct answer. The interviewer is only the to gather data, the hiring committee makes the decision and they need concrete days to look at. "Take my word for it" doesn't fly as an interviewer.
