I'm not sure what minimum wage would be competitive with a food ordering kiosk, but I'm pretty sure it's not $15.
There are many jobs that are mechanized or computerized now that required the attention of a human being in 1938.
The labor supply and demand equation would suggest the minimum wage should now be less than $0.25 in 1938 dollars.
"Your kids are starving. Carl's Jr. believes no child should go hungry. You are an unfit mother. Your children will be placed in the custody of Carl's Jr. Carl's Jr., F--- you, I'm eating."