Last week, while addressing an AFL-CIO crowd, President Obama extolled the virtues of empowering union bosses as employees’ exclusive representatives. But here is something he failed to mention while praising union monopoly bargaining: It often hurts America’s most productive workers.

Union bosses almost always resist pay plans that take into account individual effort or ability. Consequently, union contracts routinely lower the earnings of the most productive front-line workers. And employees who work especially hard or are especially talented are not the only victims.