What interests me, and always has, is the way that social class, education level, and political perspective relate to religious orientation/denominational loyalty. It is interesting that those very groups that you mention as being among the wealthiest, the Quakers and UU's, are also among the most progressive. Such people are wary of religious hierarchy and dogma. The Unitarians, Universalists, and Quakers were a refuge for suffragists and abolitionists in the nineteenth-century. Likewise, today those who are drawn toward liberal politics are also drawn toward higher education and heterodox spirituality. This is, as you suggest, in part a product of their middle-class and owning class upbringing which emphasizes individuality and leadership skills and which promotes a sense of entitlement in the child.
Also, I would be interested to find out what percentage of UU congregants and Friends are convinced or "recovering" from other religious communities. I imagine that in the last thirty years, that number is increasing as the mainline Protestant Church begins to lose its appeal with liberals disenchanted with Protestantism's rightward swing. If that is the case, we may be looking at a phenomenon in which well-educated liberals are fleeing toward spiritual communities that provide refuge from fundamentalism and its encroachment upon the formerly liberal seminaries and congregations.
I grew up as a PK with a very liberal, feminist preacher Dad who has since fled the church to become an atheist. He and I went to the same seminary twenty years apart. In that short time, the Protestant seminary's emphasis on intellectual rigor and social justice was replaced by a creeping fundamentalism and intolerance.Well-educated folks have a difficult time tolerating that perspective. I know that I found it unbearable enough that it necessitated withdrawal from seminary and from the faith of my childhood. I'm a Neo-Pagan and attend a Quaker meeting. I also attend a UU church. Most everyone I know there came from some other denomination that let them down.
I don't deny that I'm also irritated with unconscious privilege among (white), well-to-do Friends. However, I feel that we should further explore the issue of wealth and education among Friends to determine exactly what's going on here. Is there a difference between convinced and birthright Friends related to this issue? Are we intentionally excluding working people without advanced degrees or are we failing to attract them? Why don't we appeal to working people? (I ask the same question as an educator, a feminist, and a person).I think for me the issue remains with the question of ignorance and how the wealthy manipulate it consciously and unconsciously. As an educator, I believe that a liberal education that exposes the individual to the complexity and diversity of her/his brothers and sisters is critical to the process of empowerment. Education is, in many ways, the opposite of indoctrination. Fundamentalist, Mainline, and Charismatic congregations are full of working class folks which the leadership manipulate easily and often cruelly. Watching these congregations and studying their theology also leads me to conclude that they are growing in power in numbers because we have a dangerous anti-intellectual bias in this nation among working people. This bias is not accidental and its development can be traced as a historical phenomenon. Likewise, Quakers and UU's have long been associated with the middle-classes, especially the well-educated middle-classes. They also have a long tradition within the United States of being the greatest advocates of social justice.