I think it is a bit of a fallacy to group all immigrants into one basket. My ancestral line is heavily German, and my paternal lineage is directly from Germany, having immigrated in the late 1800s. The Germans of that group often formed "german town" - they moved out into the territories surrounding cities and built communities that operated in much the same way that their townships back home did. They farmed, started up factories and mills, etc. While they were often proud of their German lineage and ethnicity - they saw this as being completely compatible with the goals of being an American. It was possible to be both a German and American in terms of culture. Members of my family, from both sides, would even go on to fight against Germany in the world wars that would follow.
All of this said, the Germans would hold their own English classes. Members of their communities, who knew English, would serve as teachers to others in the community who also learned English. Depending on exactly which community we are talking about, and what time period, children in the house were often prohibited from speaking German. It was considered imperative for the success of the community for the group to integrate with the surrounding society.
The problem tends to come from regions of the world where the very concept of law and order is different. The Europeans who immigrate to the U.S. largely saw it as the realization of everything they hoped to achieve from the French and other revolutions, which ultimately fell flat. Many of the people who left Europe were, also, the ambitious among their peers. The groups who immigrate tend to be younger, of higher intelligence, and of greater motivation than the background population from where they immigrate. This is a very different case when we begin looking at people who are smuggled in across the border to fill cheap labor and *** slavery demands. When they are brought in as part of a clandestine underground of operatives and social activists - we are discussing a very different group of people from those who are looking to move.
We are also discussing a different group from refugees. Refugees are very different from immigrants in their circumstances, and in their composure. When refugees are fleeing the consequences of their own social makeup, one must question the logic of then moving to consider those individuals citizens of your own nation with the power of consequence in governing and social decisions. Allowing the people who are being conquered by their own vandals to begin tearing down your legal institutions in the pursuit of some kind of equality is asking to be conquered by the same vandals.