Node delete doesn't delete from DB
How is cron being called? (drush, wget, manually run).

node_delete requires the permission delete to actually execute the delete queries.

Depending on how you run cron will depend on the result, for example if cron is run from wget then it's run as an anonymous user therefore nothing will happen as hopefully anonymous user can't delete content.

If you try calling cron from status report while logged in as uid 1 then it should delete fine.