I left AWS before Aurora was introduced, but I suspect it's similar to how S3 fulfills a similar promise. From the S3 FAQ[1]:
> Amazon S3 Standard, S3 Standard-Infrequent Access, and Amazon Glacier storage classes replicate data across a minimum of three AZs to protect against the loss of one entire AZ. This remains true in Regions where fewer than three AZs are publicly available.
Glacier in particular seems to attract the speculative fascination. Do people not realise the name is not in jest, it really is done with graphene-doped room-temperature ice crystals and laser interference lithography?
It's not publicly available, but it was an internal AWS talk and very-deep-dive on the design & implementation of S3. A real eye opener for what it meant to build at global scale.
It's worth joining a global-scale tech company (AWS, Google, Azure, Facebook) just to have your mind blown by some of the internal materials.
> Amazon S3 Standard, S3 Standard-Infrequent Access, and Amazon Glacier storage classes replicate data across a minimum of three AZs to protect against the loss of one entire AZ. This remains true in Regions where fewer than three AZs are publicly available.
Italic emphasis is mine.
[1] https://aws.amazon.com/s3/faqs/