Agreed with the above statement. They are mostly in Economy class. Our only border is shared with the US, so go figure. Not much of a wiggle room, unlike Europe. Not that there is anything wrong with having the doors open to refugees, but you would think anyone seeking asylum would do it as soon as they meet the border. I have heard of cases, the first question they ask is "Why didn't you seek asylum as soon as you got here?", "Why did you have to wait so long?", "Why did you apply when your visa ran out?", etc. And these questions raise some red flags if you're not prepared. But as
btbt mentioned, some countries go sideways when their citizens are on visa in Canada.