This nonsensical argument is like saying we should not have drug laws since the rich can get them in other countries.  Governments cannot shirk their responsibilities on the basis of what other governments do.  If Canada legalizes cocaine use, or prostitution, or incest, that does not mean we have to do so as well.  If it does, then we need to abolish our entire  legislative process since virtually everything we make illegal is legal somewhere else.

Also, we are not limited to passing only those laws that we know beforehand will be evenly applied across all socio-economic groups.  We know that laws against robbery and drugs impact the poor more than the rich, while insider trading, stock manipulation, and tax evasion laws impact the rich more than the poor.  Yet we enforce all of them.

Now, if the point of this is that prohibiting abortion is discriminatory, that is correct.  When abortion is illegal, a child is safer in the womb of a poor woman than a rich one, since wealthy parents can afford to take their children outside the country to be killed.