AddressComplete seems to be just using Loqate Address Capture
Looking at the JS source and the API documentation it seems pretty certain that Canada Post is just using the third party service by Loqate (new name of company). Canada Post's prices seem to be much more expensive.
The API seems to be fairly similar, if not the same, so presumably someone could fork this extension is use it with Loqate. I'm considering using Loqate (currently testing this extension along with some custom integration for Drupal Webform).
Not sure if there's any action necessary here.