People are going to be crossing borders at relatively few and well understood locations.
And they could've simply imposed large fines for anyone who tried to sneak through.
It’s a bit like saying New York should close its borders with Pennsylvania
This was already done and the infection rates are still sky high.
Lots of posters here seem convinced that being an island makes it easy to control covid. If thats the most important factor, I'd love to hear some theories on why the numbers in canada aren't coming down to 0, like they have in Australia and NZ?
The numbers are coming down (slowly) in Montreal now that they have a strict lockdown. I think the process could work; but at this point it might take so long to get the numbers under control that people wouldn't tolerate it. Especially not when the vaccine feels so close. We'd be talking like, 4 months in a row of strict lockdown + business closures.
The other aspect is contact tracing. When numbers are very low, its much easier to do diligent contact tracing around every infected person. In the recent outbreak in Sydney they tracked down and personally contacted everyone they could place in the vicinity of an infected person and asked them to self isolate. By the time a handful of those people tested positive, most of them had already been isolating and as a result didn't infect anyone - which broke the chain of transmission. We could do that because the number of new cases was only around ~10/day. That would be way less feasible at Montreal's 1600 cases/day.