It's worth noting here, the two instances where the author wished for an "undo" (dropping a data database table and deleting a production server) are very diffe

It's worth noting here, the two instances where the author wished for an "undo" (dropping a data database table and deleting a production server) are very different from what the rest of the article discusses (user-facing apps like Gmail, Photoshop). A database or IaaS application are typically used by administrators, and typically every action is rehearsed in the form of staging testing or automated tests. Furthermore, these types of applications would need significant additions or rearchitecture to account for undo operations. For example a SQL implementation might not be able to reclaim disk space as well if it were unable to really delete the data from a dropped table. Likewise an infrastructure platform would need to keep unused resources busy. In both systems there are important ramifications of the deletion, and providing the ability to undo them doesn't exactly make sense.