While that’s true, I trust PostgreSQL to store exactly what I’ve asked it to store. At some point, you have to trust something to do its job, or else everything built on top of it is a castle of sand.

Imagine a bug like this in ext4. No one would reasonably contend that the layers on top of it should be validating that the files you write out are the ones you’ll read back in. We write unit tests for all kinds of stuff, but we’re not that thorough.