Won’t the market pretty well extend the minimum wage? Not to disagree with the premise, but in Germany, for example, the union represents about 1/3 of workers, and whatever the union is able to negotiate basically becomes standard for all workers. Why? Because people will gravitate to those jobs with a protected floor.
If in 6 months wages in other sectors don’t follow, then the workers will drain toward fast food and the other industries will have to be competitive.
But yes, I don’t see why the law is discriminating here. Just raise the whole minimum wage.