> Japan is a good real world example that you do not need to lean on immigrant labor to stop your country from becoming "dirty"; it's one of the most ethically homogeneous countries and also one of the cleanest places you can visit.

It's also one of the worst developed nation economies and has a massive old, shrinking population problem and is well associated with people having no kids, having no prospects for a better life, and having huge amounts of its population live alone shuttered from the outside world.

A good economy has many benefits and skilled immigration can significantly improve developed nation economies.