[aaauaucuggaa]

a few examples that come to mind: EC2, EMR, ECR, EKS, RDS, EBS, DMS, ECS, VPC, SSS (S3), SNS, SES, IAM,

[saurik]

How does this list show these are easier to remember than ones with four characters?

[singlow]

The claim was that amazon prefers 3 letters, so the list supports that claim.

[LilBytes]

And of course, AWS.