How to create Drupal view to show CiviEvents and Drupal Events
I don't think you are missing anything obvious. They are completely different Entity Types so you can't do this in a single view.

This is a constraint of Views.

If you were to create a Drupal node linked to each CiviEvent (using CiviCRM Entities) then you would be able to display all items as 'content' and provide links to the Info and Registration pages from that.

There has been some good documentation about doing that by skvare.com