Yeah but the thing is that many immigrants that have been placed in more scarcely populated areas dont want to live there and decide to move to larger cities where they then live in ghetto suburbs with their fellow countrymen.
I understand where you are coming from. I live in Finland and have seen this happen in real life. The reason they move is due to racism, living ethnic counterparts and job opportunities.
I live in the capital, Helsinki. It has for long fought economic segregation. Long before immigrants came, the capital was being split into poor and rich neighbourhoods. To combat this, the city council demanded that affordable housing to be built around the city. You had mixed neighbourhoods.
When somalis came here, we settled around the city because of this policy. Of course some areas have bigger somali population. This resulted us not being segregated. Its actually good.
Point is, the lawmakers have the power to inforce integration.