Tipped wages are a holdover from slavery. After the civil war, freed slaves were a huge percentage of servers (both men and women). So the tipped wage as a sub-standard wage was set to maintain the class system: If a black person wants to survive, they must suck up to the (mostly) white patrons.

This is why, when the minimum wage became law (1938 IIRC) a "sub-minimal wage" (how's that for an oxymoron?) was created to keep black Americans firmly in their place in segregated America.