Sorry, I somehow missed this and not sure why we need to throw around aspersions when having a discussion, but no that's not what I want.
What I am saying is:
The ideal approach is to take the average hourly rate that your daughter makes and deems worth doing the job for and give that dollar amount and do away with the tipping. $25/hour and no tips, for example, or whatever it is. I think we all agree that this will never happen because while restaurant owners will try to push that cost on diners, restaurant owners probably can't increase prices to where they need to be for us to bear the full cost and remain competitive or reasonable, and will have to eat some of it. Pun intended and owners won't generally want to do this.
The current approach: $2.13/hr + tips (20-25% being the socially acceptable standard). This has your daughter and her peers making some number of money that they deem acceptable which you've implied is much higher than $15/hour.
If servers/society wants to change the server/diner model and offer: $15/hr + tips, then my argument is that the socially acceptable standard should be lowered from the 20-25% to keep servers making the money they currently deem acceptable, whatever that is. The diners/consumer ought to be given the option to, by paying the listed menu price for the food on a menu, happily accept the restaurant owner footing the cost of the living wage for their employees versus the diner.