Through mid life, your financial health is not as determined by wages, but by your family/connections. Do you have access to a grandmother who can babysit? A decent second-hand car? A good roommate situation? Just look at the expense table - any one of these things could be worth up to 20% of your income!
And you see that literally right here - are any of us actually comfortable with the idea that the value of your labor should be determined by your marriage status and number of children?
It's kind of telling that countries with "successful" minimum wages either don't have one and just institutionalize collective bargaining, or they do some fancy calculations that start with prevailing median wages and welfare eligibility. The idea of trying to get this number from the bottom up by building expenses just doesn't seem very robust.