It cannot be a good omen for the American economy that the most compelling reality shows echo the class tension and overnight success fantasies of movies produced in, or set in, the Great Depression. But the unquenchable appeal of "The Apprentice" and "American Idol" lies at least in part in their poignancy: both series combine the preposterous feel-good optimism of "42nd Street" with the desperation of "They Shoot Horses, Don't They?"