Workers are struggling to stay afloat. Incomes haven't gone up in the 21st century. Inequality reaches new extremes. A record portion of our national income goes to corporate profits, while a record low goes into workers' wages. Three-fourths of Americans fear their children will fare less well than they have. This Labor Day, we should do more than celebrate workers -- we should understand how vital empowering workers and reviving worker unions is to rebuilding a broad middle class. The raging debate on inequality and its remedies often omits discussion of unions and workers' power. Our extreme inequality is attributed largely to globalization and technology that have transformed our economy. But this leaves power and politics out of the equation.