With regards to migration, a sovereign nation has the right to affect border controls as it sees fit. Free migration without border controls undermines the sovereignty of the state. As it stands, in first world nations there is no restriction on the ability of potential immigrants on the ability to apply as long as the application itself is complete. However, the right to approve or reject said application is entirely at the prerogative of the immigrations department.

But why should the immigration department have the right to reject people from movement? When workers rely on state for authorization of movement it causes workers to to rely on the wages from the owners of the means of production. How come indivdual and international states have the right to monopolize the right to authorize movement? We're essentially dependant on creating separations between bodies of citizens singling out those who were lucky enough to be born in a richer and more developed country.

Even disregarding the sovereignty issue, there are practical considerations to make. You severely underestimate the number of potential immigrants precisely because of the effectiveness of border controls. If unrestricted migration were to occur, the overload on public services would be immediate and disastrous. Our society is stable because it has developed an equilibrium which is completely dependent on its ability to handle change. The humanitarian crisis that would result would almost certainly destabilize any nation that was naive enough to adopt it.

I completely agree with you in terms of population control. I mean, I'm not too sure how to get around that since this is all theoretical but a solution could be to have less and less filtering and restrictions and over time work our way up to free mobility.

On a final note, you mentioned you were Canadian. Canada is one of the nations which is most capable (if not the most capable) of absorbing immigrants due to two factors:

1) The sheer amount of space. If you can get past the cold, the natural riches of the land have huge carrying potential in terms of population. Compare this with Europe, where population density is orders of magnitude.

2) The ease of border controls. Canada is buffered by the Arctic circle, Arctic ocean, Pacific ocean and the US. As a result, you don't have waves of desperate migrants coming by ship or by land. That is a huge advantage that other nations simply don't have. Every East Asian nation dreads the day North Korea falls because of the tsunami of refugees that would result

Also agreed. Canada is definitely at an advantage. Like I said though, ofcourse this is just a flawed theory when put into practice it would have to be gradual. The benifits would also be long term.