I also suspect that this subject is a bit like finding 'requited' love songs--those who HAVE love are too busy to write and sing. One has to consider where the impulse to compose and create comes from: 'conservatism' and 'right-wing' very often describes those who are very much involved in setting limits on others, or preserving privileges for certain groups.(yes, I know that is far too simplistic) So, when I see people who define themselves as conservative, they usually appear(at least to me) to be people who either do not 'make music' or adhere to strict limits in what they DO sing..(patriotic songs, church music of certain types..etc). Of course there are exceptions...I am just arguing that from the beginning, music has often been a way to express one's personality and ideals...and the creating, singing, collecting and preserving of folk songs simply tends to be weighted toward those aspects of life which involve the liberalish, left-wingish aspects of the human condition.
(there's probably 2 or 3 PhD theses here if one had the time & inclination...I think I'll go sing something instead)