I think it's class based more than anything, but it's more complex than assigning a single cause.
Mexico City, for example, has plenty of malls, and a decent number of immigrants are from other countries in Central and South America, all places that have malls in the cities.
From the immigrant laborers I've talked to, they mostly seem to come from small towns and village in their home countries and remit as much money as they can back home. On top of that, they usually command lower pay than the domestic laborers in the same market, so this leaves them with very little in the way of spending money. They also work relentless hours, 7 days a week. So their life is basically wake, work, sleep with stops for meals 3 times a day.
There are more than just workers though, the women who come tend to end up in lower-end service jobs, house cleaners, cheap day care etc. And some of them have kids who are right now, very young and not in the job market (meaning no disposable income).
Both groups are well serviced by their local Mercado Latino and Walmart in terms of most needs and their children, if they've brought them here, are usually too young to want to shop at stylish mall shops.
If you look at the kinds of places that service the community, they aren't high-end restaurants and retail shops offering comforts from home. It's cheap fast food, pupusa shops, check cashing, cheap phone calls home etc. A visit to local pawn shops in and around Manassas will reveal shelf after shelf full of tools laborers have sold as they head back home after the housing bust, and are usually in shopping centers full of Spanish language shops. It's very much a temporary laborer blue collar demographic.
I suspect this will change. Folks I know who came here during the early parts of the Salvadoran Civil War now have kids old enough to care about such things and are generally well integrated, educated and affluent.