[WS:] I think it is a very narrow econo-centric understanding of elections, and institutions in general. A 'uses and gratifications" http://en.wikipedia.org/wiki/Uses_and_gratifications_theory approach, popular in certain areas of sociology, claims that people use institutions in many different ways that have nothing to do with narrowly defined 'economic interests.' People may vote for such diverse reasons as patriotic duty, identification with a social group or a person, vicarious bashing of real or perceived enemies or scapegoats, hatred, habit, pride to name a few - none of which has anything to do with economic interests.
Republicans understand this very well and appeal to these different sentiments. Liberals and lefties, otoh, seem to be stuck in the box of "self interests."
Wojtek