Yes, absolutely. That is certainly the case in teaching, which is not surprising. Teachers have to do compulsory unpaid practicums. However, they are not the only ones doing that. Nurses and psychologists also have to. PhD psychology students have unpaid placements. That is a problem. In many cases, they receive the same workload as professionals. It is true that they do not have their degrees yet. But the fact remains that they are asked to do the same amount of work as professionals, sometimes with supervision but sometimes without. In addition, they are not compensated accordingly. But that's important. They are doing the same tasks. I agree that they should not receive the same salary. That's obvious. However, adequate financial compensation should be provided for those internships.
On April 1st, 2014. See this statement in context.