I think it's time for AWS to pull the curtain back a bit and release a JSON document that shows a list of all internal service dependencies for each AWS service.
Could we have had an offsite location to fail over to? From a technical perspective, sure. Same as you could go multi-region or multi-cloud or turn on some servers at hetzner or whatever. There's nothing better or worse about the cloud here - you always have the ability to design with resilience for whatever happens short of the internet on the whole breaking somehow.
Short of publicly releasing all internal documentation, there's not much that can make the AWS infrastructure reasonably clear to an outsider. Reading and understanding all of this also would be rather futile without actual access to source code and observability.