I don't understand how this is even possible in a company operating on that scale. Granted, I'm a lowly scientific programmer with no clue about running a cloud

I don't understand how this is even possible in a company operating on that scale. Granted, I'm a lowly scientific programmer with no clue about running a cloud infrastructure, but I would have imagined that there would be at least a pretense of oversight for destructive commands run in such an environment. A scheme as simple as "any destructive command run on S3 subsystems is automatically run in a dry run form, and requires independent confirmation by 2-3 other engineers to actually come into effect" would have prevented this altogether. Given the overall prominence of S3, this incident seems to demonstrate a rather callous attitude on the part of the organization.