Under U.S. federal law, age discrimination not only protects exclusively the old against the young, it also protects only those over 40.[1] Discrimination in the workplace and in public policy against the young is a big problem (in the moral sense, perhaps not an economic sense) that really has, as far as I can tell, political recognition among essentially no one.
1: http://www.eeoc.gov/laws/types/age.cfm