It's not just some quirky viewpoint in America, it's built into our labor laws. The $2.92/hour is the rate that Waffle House pays her provided she makes (and reports) enough tips to exceed or equal either the higher of the federal/state minimum or a higher agreed rate. At the moment I can't recall whether this calculation is per pay period or per shift though.

Requisite disclaimer: I'm do not support tipping as a primary means of paying for labor. I'd love to outlaw the practice, not the least of which because it's highly discriminatory.