The Service Employees International Union last week held yet another national protest. The “racial justice-themed Fight for $15 day of action” spread to dozens of cities but failed to live up to the hype.

A few dozen people showed up in Boston. The turnout appeared even smaller in San Diego. The Chicago Coalition for the Homeless tweeted a picture of “16 homeless workers.” The union should be embarrassed. Ignore the SEIU’s political theatrics and Potemkin protests, and you’ll find a cash-strapped group waging a losing war....