If restaurants tripled their wages they would triple their prices to compensate, and there would be no people eating in those restaurants. Then there would be no restaurants for those folks to work in. It ins't that simple. Desired wages are the individual's motivation to get employment that meets employees' wants in life. If working at Subway 35 hours a week for $10 an hour doesn't pay for my apartment, vehicle, and food, I have two choices.
1) Apply somewhere that gives me wages and hours that meet what I need to live.
2) Complain that I don't get paid enough.
Neither of those is the responsibility of society as a whole to fix.
I am not talking about changing the server's total compensation. I am just saying it doesn't make sense that they get $4 per hour from their employer and then $11 per hour from tips. Just pay them $15/hour and increase the menu prices accordingly. Whether I am paying $40 for a meal plus $10 in tip, or whether I am paying $50 for the meal and don't have to worry about the stupidity of the gratuity system, my bottom line is affected similarly.
And tripled wages does not equate to tripled prices...the cost of labor for servers is just one small part of the overall cost in getting a meal to the table.