The Service Employees International Union (SEIU) has spent millions of dollars on campaigns over the last three years in an effort to improve the wages of employees in the fast-food and retail industries. It is unclear how the SEIU benefits from bankrolling these campaigns. Over the past three years the SEIU has not gained a single new member from fast-food industry. Fast-food workers have proved to be difficult to organize due to the high turnover rate within the industry.
See "Union Spends Big on Low-Wage Campaign, Endgame Unclear", The New York Times, April 14, 2015