Last quarter, for instance, McDonald's ( MCD) labor costs for company owned restaurants were 25.7%% of sales. For Wendy's ( WEN), labor costs were 29.1% of sales last quarter; for Denny's 40.1%. While it's not clear what the exact impact of $15 per hour wages would be, suffice it to say that it would be significant, and any resulting cost increases would be passed on to customers who hold the keys here. Either they will pay more for a burger and fries, or they won't. Follow @JonMHellerCFA This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.