I refuse to believe that's true. That they were denying Dorothy (92) from going through customs because she couldn't use an app. That's an extraordinary claim.
If they weren't denying Dorothy, that means you did not need an app.
From what I'm reading, non-users weren't and couldn't have actually been denied entry. It wouldn't have held up in court either. They could be made to quarantine.
https://en.wikipedia.org/wiki/ArriveCAN