The same things that caused it here.. and for the same reasons.. extending the welfare state and buying votes. The potential difference in how we respond vs Europe will come from the fact we have a Constitution that compels us in the right direction. They do not have any such limitations on government so any solutions they pursue will invariably be Fascistic and isolationist. It there’s a bright side to a ten year perspective on Europe, it could be the end of tolerating mooslime immigration.
We’re at least starting to see some lip service on your point about immigration. Unfortunately, it seems to be just that. How many no go zones does a country need before lip service turns into something concrete?