That is odd. In process designer if you add an automatic action into the request process, what list of actions do you have available?
Much like Incident Management uses "Add Reminder", Request Management uses "Notification". It's all considered "Reminders" in the business object, it's just the action name is different.
Got it! The default window is different, so I mistakenly figured there was a different BO at the heart. Sure enough, if I try to modify the BO associated with a Notification action, I get the Reminder BO. My oversight.