I think it is not so much of international flights but testing and tracking-14 days.
My cousin went to HK two months ago due to business and she along with everyone on her flight waited 19 hours at the HK airport in order to wait for their test results, then not only did they need to download a tracing app, they were also handed out a bracelet(like the ones in Hospital), and its showed as a sign these people should be isolated for 14 days. The Govt even provided hotel rooms for them to stay. If the medical worker see the bracelet is cutoff when they come to collect it in 14 days, you will be in jail-no questions ask.
Then when she comes back to Vancouver, there is test at arrival and then never heard a word from CDC or the govt or tracers.
Not sure about you, but one City is certainly doing a whole lot more to prevent it from spreading while the other is going with the homie system.
Then you have Australia, this might sound make up but that’s what happened to my friend, she was travelling in the pacific islands during March when every countries started to lockdown. She was stranded on an island outside Fiji or Somoa, so finally when the borders started to reopen, she managed to get into Aus. and awaiting to transfer out to HK, but the moment the govt knew her transfer flight is in 2 days, she was picked up by the police and CDC and sent to one of the govt designated hotel. FYI, the police and CDC were very polite and nice. She even made jokes about having police escort in a good way. I don’t see Canada and the US ever doing that.