Union activists want to raise the minimum wage in the fast-food industry to $15 an hour. However, fast-food restaurants operate on very small profit margins; they could only afford such wages by raising prices—significantly. Higher prices would, in turn, drive customers away, forcing even larger price increases to cover costs. Ultimately, the average fast-food restaurant would have to raise prices by nearly two-fifths. This would cause sales to drop by more than one-third, and profits to fall by more than three-quarters. Absent the widespread adoption of labor-saving technology, the union-led “Fight for 15” would make fast food much more expensive for Americans.
http://www.heritage.org/research/reports/2014/09/higher-fast-food-wages-higher-fast-food-prices