Originally Posted by
expert7700
To test everyone at YYZ would a monumental workload with hours of bottlenecks for arriving passengers. I've been at YYZ during peak arrival time to see the customs arrivals hall backed up all the way to the escalators, causing a hazard requiring the emergency stop button to be used. Then throw in some extra widebody diversions from other cities due to winter weather....
Testing everyone seems to work for many other countries who are already doing it. They don't have logistical issues.