I'm not going to rehearse my lines about economic and cultural factors being entwined again—you could just go back and read the posts—but it's frustrating to be accused of over-simplifying because I have, out of rhetorical necessity, insisted that the economic factors be considered.
When I say for example "personal connections [in driving the concentration of wealth] ... are racialised in weird ways" it should be clear that I'm alluding to the entanglement of difference in social and economic dynamics.
Hate to go on an antagonistic nit-picking spree, but nothing you've written here or else provides an actual causal mechanism of why immigrants do or do not integrate.
I don't regard myself as having a burden of proof there. I pointed out that it's absurd to hold any migrant group responsible for not being assimilated if they don't control many of the social mechanisms that can decide the question. That is not an argument about causation—it's a critique of an argument about causation.
However, taking Australia as an example, it can be argued from this country's post-settlement history that the mainstream has always decided when migrant minorities will be integrated.
English and Protestant settlers, after vilifying Irish Catholic migrants for decades, allowed the Irish to join the mainstream when Australia redefined itself as a white nation at the time of Federation.
The Anglo-Irish mainstream decided that so-called "wogs" could actually be Australians during the period of rapid expansion after WWII, when refugees from Greece and Italy arrived in large numbers.
In the late 1960s, the White Australia Policy was pulled apart by the then economically liberal government hoping to boost migration and drive down the price of labour.
In the 1980s, East Asians began to be accepted into the community with the arrival of Vietnamese refugees, and the previously powerful force of anti-Asian xenophobia stopped very suddenly.
Before their integration into Australian national mythology, each of these migrant groups had been vilified in mainstream culture for its backwardness, degeneracy, heretical religious practices, morally dissolute behaviour—arguments reflecting the view that certain virtues "inhere" in culture, or that certain groups lack "human capital".
Australian politicians used to make much more over the top claims about the Irish in the 1860s than they do about Muslims now.
Looking at this history and its cyclical structure, it makes a lot of sense to be suspicious about arguments about cultural difference as they apply to extremely diverse Islamic refugee populations from Afghanistan, Iran, Myanmar, Syria ... the cultural differentials that matter more when it comes to integration are those of the mainstream, not the new arrivals.
As you point out, the US is somewhat special in this regard with its relatively rapid acceptance of migrants from different nations—if I had to guess, I'd suggest it's because of American migrant history and its different development.
