The initiative for a $15 minimum wage has some very far-reaching consequences.
Hypothetically, I own a small manufacturing business. I pay a janitor $10 an hour and now have to increase that to $15. But I have an office clerk I am paying $15, and I have to now increase that to $20 to reflect the differential contribution they are making to the business.
I have a material handler making $20 and must increase that to $25 for the same reason. I have a machine operator at $25 and now must pay $30. I have a mechanic at $30 and now must pay $35. I have a tool and die maker at $35 and now must pay $40. I have a supervisor at $40 and now need to pay him/her $50 an hour.
All of a sudden my labor costs have not increased only by having to pay my janitor the new minimum wage of $15 per hour. My labor costs have increased significantly by having to increase the wages of everyone in my employ in order to properly reflect the differential contributions they are making to the business.
My only recourse is to raise prices for my product. Perhaps not enough consumers are willing to pay the increased price. In that case, I am out of business and my employees are out of a job. Including the janitor whose wage was raised by the government to $15 an hour.