Right now, the US doesn't have open borders and inclusive welfare system. Thus legal migrants are better integrated. Although, as Heritage has shown, illegal migrants cost a lot of money for taxpayers (source).
Let us look at European countries where most of the migrants are eligible for welfare:
Sweden: just 21% of Somalis are employed (60% in the US, for comparison). (source)
The Netherlands: the huge proportion of non-EU migrants are sitting on welfare (Natives - 2%, Somalis - 70%, Syrians - 60%, Iraqis - 60%, and etc). (source)
P.S.: What's happening with this sub? People are downvoted for questions and facts.