Im not super informed on this topic, but i do remember learning about this In school.
So In Denmark (& Sweden) we have alot people from different ethnical backgrounds, like Turkey, Iran, Irak, Somalia etc. There was a time (I think 1980-2005)
Where a lot of the people from foreign countries started to seek what you can call “The American Dream” type of thing. Basically people were trying to seek a better place to live, for better schools, better job and a better place to raise their kids.
Because back In their home country, opportunities were low.. in the beginning they overtook a lot of the low jobs like cleaning in public etc..
This is what I remember learning abit about. There is probally someone who knows the story better but this should give you abit of an idea of why/what.