Since fast-food workers got a raise, they didn’t quit as often. Employers were therefore able to save on recruiting new workers. This saving allowed them to continue employing just as many workers without any loss of profits.

The increase in the minimum wage didn’t lead to the elimination of minimum-wage fast-food jobs. Besides, if anything, laying off higher-paid supervisors would let the companies save even more money.

In other words, if wage increases would lower profits, then fast-food companies would lay off workers. But this doesn't tell us how fast-food companies were able to maintain their profitability, so it's not helpful.

Exceptions aside, we know that most fast-food employees are paid minimum wage, so we still need to know why they weren’t laid off when costs rose due to the minimum wage increase.

So fast-food companies did not see higher sales from minimum-wage workers due to the recent change. This eliminates a possible reason that layoffs didn't take place, but doesn't get us any closer to an explanation.