[Answer]-Default django auth schema doesn't create reference between users and groups

SQLite recommends using the REFERENCES syntax, and full FOREIGN KEY support requires an extra pragma switch.

Historically, SQLite did not support FOREIGN KEY constraints at all, and when they were added it was with an explicit per-connection switch to turn this on to retain backwards compatibility. For Django, using REFERENCES suffices, does not limit Django to the more recent versions and saves having to enable the FOREIGN KEY support or detecting that the feature has been compiled in.