We handle the system-level administration of the server itself. Wal_level, for example, can only be set at server start. We set that in the config file, which users can't edit.

Users receive superuser on a blank slate Postgres, and they can do whatever they like within the already-running Postgres server -- create/delete/update databases, users/roles, privileges, and so on.

We are seeking users who don't want to worry about wal_levels and things like that -- users who just want a Postgres server to use, with the assurance that backups, OS patches, and so on are all taken care of for them.