There is a fascinating paradox within Mormonism. There is the general perception among many that this church caters to the poor and uneducated and ignorant and desperate. In fact, if you ask members themselves to identify the "best potential converts", I would be willing to bet that many would identify exactly this group - the poor, humbled ones.
Contrast that with the actual demographic descriptions that often are published in comparative studies of various religions. In all of them I have seen, members of The Church of Jesus Christ of Latter-day Saints are aggregated as (among, at least) the most educated believers in the world - with a standard of living that also is near or at the top of the lists.
The question in my mind that rarely is discussed or addressed in these studies is whether both of these seemingly opposing claims are true - that the nature of the Gospel that we teach appeals to the poor and oppressed initially and then, in very real and practical terms, inspires and motivates and literally "empowers" those who stick with it to raise their education and/or standard of living - if not with the initial converts, then at least with their children. I suspect the "middle class" perception of the Church from the outside is a result more of this growth from generation to generation (how 2nd and 3rd generation Mormons appear and live) than it is to the status of converts when they first join the Church.
In that sense, if those around them tend to remain in poverty while Mormons (outside of America) tend to raise their standard of living in ways measurably different than those around them, then perhaps that contributes to the impression that these Mormons are more "American" than "native" - simply because they act and dress and carry themselves more "middle-class" than their friends and neighbors. (Fwiw, I have heard critics say that converts in poorer countries join the Church simply to "get a better education and make more money". How's that for a warped criticism - whether it's true or not?)
It would be an interesting way to explain the oddity that those in developing countries who become established in Mormon culture tend to raise their standard of living relatively high enough to have excess within their culture, while those who have enjoyed multi-generational prosperity tend to succumb more to the allure of their prosperity, over-extend and lose it. (Sounds like I'm paraphrasing the Book of Mormon, doesn't it?)
There is a good spiritual lesson in there for anyone who wants to look for it.