Nice try, but as with most liberal arguments, your simplistic theory proves itself to be complete bullshit. The minimum wage for younger workers in Australia is actually around $8/hr so McD's simply relies on them to make up for the higher overall minimum wage. And in France, they've fired all of their order takers and replaced them with automated ordering machines.

It sounds nice and heartwarming to give everyone earning the minimum wage an increase in salary, but the fact is all you're going to do is temporarily upset the apple cart until the free market adjusts to the increase.