>Why do we treat those groups differently then?Because it's much easier and safer to integrate people with the same religion, ethnicity, that come form a peaceful country with a good track record in STEM[1], meaning they have a high chance they will integrate well with the locals and be productive, with a low chance of unemployment, crime and social unrest that usually comes from importing people from countries with a long history of extreme poverty, crime, civil wars, LGBT & human rights abuse, poor education and religious fanatism.
It's not racist to see that 2+2=4 and call a spade a spade.
[1] Ukraine is 15th place in the world in terms of medal count at the international math Olympiad, ahead of many richer countries like France, Italy, Sweden, Netherlands, Austria, and is home to manufacturers of planes and jet engines and other engineering marvels like the Antonov 225