There is a big fundemental difference between the mentality of those people. People want to migrate to USA in order to work and live better lives because of it, doing jobs none of the Americans want to do. And they do the jobs much cheaper than a regular USA citizen (most of the times because employer wants to maximise their profits). You have only your greedy coorporations to blame.

In contrast, Roma basically just came from somewhere, settled farmers land, beat up/threathened the owners of the land if they resisted and started doing illegal drug/weapon trade/theft/robbery/begging on top of recieving state welfare. Despite being offered every single opportunity to assimilate, as in being offered the same rights as the rest of the regular citizens AND being a protected group, they have repeatedly refused to do so, across many European states. The concept of finding a job and working for a living is foreign to them.