I understand that you describe the status quo in many systems today.

However, besides the technical aspect you talked about the "absolute best you could expect when asking for a delete in the UI^".

I think this where I, other posters in the thread, most people, and probably the GDPR and other legislature, would disagree. We expect significantly more effort to clean up deleted data.

This includes, for example, the ability to delete datasets from backups, as well as a general accountability of how often and where all the data is stored and if, and when a deletion process is complete.