You're totally ignoring the most probable outcome - reductions in costs lead to higher dividends paid to shareholders. Consumers continue paying the same price.
Now, employer - union, maybe.
Even still, nobody's forcing them at gunpoint. Presumably they chose a an unpaid graphic design internship because they value the experience. They could have chosen to work elsewhere for pay. As long as they are not being forced, are not being deceived, and are choosing according to their own priorities, it's their decision.