I assume it's because AWS uses Gandi as their registrar.[1]
while Amazon itself uses Mark Monitor from CSC.
Re:Amazon's customer service backdoor
by asymptotic on Sunday January 24, 2016 @06:44PM
(#10964620)
You can register for domains through AWS Route 53 and it'll automagically register on Gandi with WHOIS protection and link it up inside Route 53. You then don't need to leave the AWS UI, it just seems like it works magically.
(I think this is true...I can't remember now actually).
Why do you say here and thus Amazon?