The people making the announcements, and even some of the engineers working on higher-level systems, might not even know whether the (multiple layers of the) un

The people making the announcements, and even some of the engineers working on higher-level systems, might not even know whether the (multiple layers of the) underlying storage system actually deletes or just adds a "tombstone" that won't take effect until the next compaction or equivalent. They also might not know about copies left around in caches, during rebalancing, etc. Or whether "trimming" or overwriting data on a particular device - really anything short of a full device wipe - really makes the data go away. Secure deletion is a harder problem than most people think; I certainly wouldn't assume that Google or any other organization has really handled all the corner cases. Source: I've worked on many large storage systems, including the largest (by bytes at rest) at Facebook. They were subject to the exact same kinds of requirements as Google, and as the code continued to evolve gaps would still appear from time to time.