I wish the push was more of a law that let users delete their data immediately and completely from a service with the click of a button.

Any architecture that facilitates this will lose massive amounts of customer data, full stop. Backups have to be in places where live systems can't touch them, or can append only. Backups have to be offline and immutable. If you can mutate a backup based on a user request, it's not a backup.

Offline backups are, however, pretty hard to steal (unless you're stealing the physical tapes).

So... immediately, maybe. Completely, no fucking way.

That's what encryption is for - burn the key, and the backups are useless even if they're immutable.

Which is going to throw out all the other users' data too. Unless you have one key per user, in which case those also need nontrivial backup.

Right, but eventually the older backups (still containing Joe Public's data) will go away. Depending on how long you retain backups it may be anywhere from a few days to perhaps a few months but at least it will be gone from the live systems immediately.

I second those wishes, but thats feasibly impossible without vast auditing resources. DB backups, logging, and the general "archive-first" nature of the modern web essentially prevents this from happening.....even if service providers wanted to give this opportunity to its users...and most do not.

that's true, but if such law was implemented, services providers will now have to think about running things legally or illegally.

This is exactly my concern as well.