This rationale is always based on the fact that a "teenager" doesn't need a livable wage. The problem with this, is that not every fry cook is a teenager that doesn't need to pay for food and shelter. Fast food is a $300bn industry in the US. It doesn't need to be subsidized by parents.
Also...the whole argument falls apart when you realize fast food is open during school hours. Legal working hours for teenagers start after school and end before typical closing times.
