While many Americans associate Mexican immigration with poor, rural laborers, a large number of those seeking work in the United States these daus are better-educated and hail from relatively well-to-do, middle-class backgrounds in the city. Many set aside years of training and education to illegally perform menial tasks, all of which pay better than most white-collar work in their homeland.
See "Not All Mexican Migrants Are Poor Laborers", Will Weissert, San Francisco Chronicle, May 7, 2006