I recently heard on the radio a good take on the immigration issue from some Canadian economists. They talked about a "population trap." A big question is whether we are building enough housing and infrastructure for people and how much are we using; size of housing, automobile dependency and so forth.
Here in USA, we cloud the issue as the right wing demonizes immigrants themselves while the left wing cries racism. We tend to ignore the logistics of making it work.
Is housing affordable? How are we handling traffic or are we better off relying more on public transit? Are there too many people, versus what we can provide for them as well as ourselves, or does the new human energy, from immigrants, help us develop the infrastructure we need?
Much of it is about planning.
In Canada, there is lots of land, but still the infrastructure is even smaller than ours. 400,000 new folks new moved to Canada last year plus 800,000 temporary student visas; nearly twice the flow from past decades. That's a big number trying to be absorbed into a country with smaller population than USA.
In some cases, cutting back on student visas means universities might go broke so there is that issue also.
In some cases homeowners benefit if home prices skyrocket, but renters and new homebuyers suffer; people divided.
This is mostly my own thinking not all from the show.
Both USA and especially Canada have land, but indigenous cultures like to preserve their ways of life; especially in Canada. That often requires lower population densities for fishing, hunting and so forth; not to mention mainstream culture preserving a car based society needing room, in developed areas, for parking.
Add to this the fact that much of the rest of the world is becoming unlivable due to authoritarian governments and theocracies so lots of folks are knocking on the doors of our countries.