The data is actually deleted (at least in the case of FB data) when you delete your account, having sat through several audit meetings and known people who wrot

The data is actually deleted (at least in the case of FB data) when you delete your account, having sat through several audit meetings and known people who wrote the deleter code. It is not instant, since some of the deletion has to be queued up in async jobs so that when cold storage platters are re-written it skips your photos, etc. And you are correct that EU regulations are the big stick which keep everyone toeing the line regarding what must be done when a user requests the deletion.