Enable dialog for non-admin user
The answer is simple enough, though a little counter-intuitive coming from a Drupal 7 install where everything but the kitchen sink is included.

All I had to do was to inlcude the library in my theme's .libraries.yml file;

dependencies:
  - core/drupal
  - core/jquery
  - core/jquery.once
  - core/drupal.dialog.ajax


This will be more performent than including the entire core javascript system on every page. It was a little confusing since that is the behavior for the admin user.