Because Canadians aren't crossing the border by the millions fleeing a shithole. Mexicans are.
and what are they fleeing TO? jobs. Jobs that, even though they are sub-minimum wage, are way better than what they have south of the border. If all American business owners refused to hire any illegal immigrants, those jobs would NOT be there for them and they would NO LONGER come to America in search of work. Do you deny that?
Want to stop the influx of illegal aliens across our southern border? No need to build a fence, or even patrol it.... just stop American businessmen from offering jobs to illegal immigrants. period. No jobs, no wetbacks.
Yes, eliminating the jobs would stop the few who come only to work and aren't looking for anything else. That would help a lot.
But, as long as we're handing out free food, free healthcare, free education, subsidized housing, and protection from the law in the sanctuary cities here, as well as providing fertile ground for theft, burglary, shop lifting, drug dealing, etc. etc. etc. that is much safer to do here than it is in Mexico, they're going to keep coming.
We HAVE to have and enforce laws like Arizona just passed to stop criminal activity in addition to illegal entry. And, other than one time emergency humanitarian relief, we have to pass laws to stop the anchor babies and freebies that like a magnet to many.