I was mainly referring to general wage discrimination across all industries, but here's a few references for the restaurant industry from 10 seconds of googling:
http://rocunited.org/publications/tipped-over-the-edge-gende...
– The industry follows a conscious business model of confining women to the lower-paid positions within restaurants. Women are hired for only 19 percent of chef positions, for example, even though traditionally most women are more likely to do a majority of the cooking at home.
- In addition, women are confined to the lower-paying segments of the industry such as quick-serve and family style rather than the highest-paying fine dining segment. So even within the same job classification of server, full-time, year-round female servers are paid just 68 percent of what male servers are paid ($17,000 vs. $25,000 annually).
http://fortune.com/2015/10/23/wage-gap-restaurants/
- Women and workers of color are often pushed into the lowest-paying jobs in the food service industry, according to a report from the Restaurant Opportunities Center United, a labor advocacy group.
- Women are pushed toward lower-paying jobs at more casual restaurants, and people of color are channeled toward even lower-paying jobs such as bussing and kitchen positions.