LttE - Why do we still have unions?

Submitted to the Orange County Register on 17 October 2005:

Letter-writer Bob Tucker praises unions for giving us "the eight-hour day, workplace health benefits, family leave, retirement benefits and a living wage." This just begs the question, though - with all of these things either codified into law or universally accepted by employers and employees alike, just what function are unions still serving today?

UPDATE: Printed on Wednesday 19 October 2005