I don't think Amazon compensates that much - I interviewed with them this past summer, and they tried to lowball me. I gave a firm number that I would not go below after giving some numbers I have turned down in the past, and the process stalled indefinitely. I have also heard stories about Apple lowballing friends as well, to the point startups were giving higher compensation. The others, I have heard stories about or could believe.

You were probably down leveled based on the interview. The comp will max out lower (and therefore the offer won't be able to budge significantly higher) than you may achieve somewhere that did not downlevel you.

I don't think so - I am pretty certain I aced both technical phone screens, answered the questions fast, and explained everything clearly with a high level understanding of everything asked (including all the nuances) while remaining calm & jovial the whole way. The technical screens were some of the easiest interviews I've ever had.

I should note that I didn't get to the in-person interview, and that was because salary negotiations start beforehand. I did my research afterwards, and everything I found seemed to point towards cheapness.

Having worked there, I am not sure I believe you. An SDE interview is a single phone screen before onsite. Salary is also not negotiated before an onsite + offer in hand. I was a hiring manager and often matched or exceeded competing offers from MSFT/GOOG, so our pay was not significantly different. The only difference is that Amazon base pay maxes out lower (at about 160k) and therefore RSUs make up a larger portion of salary for higher level positions.