It might not be impossible for everyone, but it's certainly a huge disincentive, and not everyone has the skills or energy to hold down another job that actually pays the bills, or to contract out. On top of that, many internships (like in finance . . . or least like finance used to be) would expect interns to work 60 or 80 hours a week, which would make any sort of additional paid labor basically impossible.
Just because some people manage to make it work doesn't mean it's not hugely discriminatory.
The thing that really galls me is that most of the time the companies that do this sort of thing are perfectly capable of paying their interns, at least well enough for them to eat and pay rent, they just choose not to because they can get away with it; there are enough college students trying to get a foot in the door and who have other support systems.
Just because some people manage to make it work doesn't mean it's not hugely discriminatory.
The thing that really galls me is that most of the time the companies that do this sort of thing are perfectly capable of paying their interns, at least well enough for them to eat and pay rent, they just choose not to because they can get away with it; there are enough college students trying to get a foot in the door and who have other support systems.