Because they can!
Because it would cost money to pay them!
Because why would you pay somebody who is desperate enough to work for free!
Bell Canada is in the news today for its methodical abuse of unpaid interns. These are young folks just out of school, desperate to have something on their resumes. Bell is one of the country's biggest and most profitable companies with net earnings of $2.6 billion dollars last year.
This is an even better scam than the Temporary Foreign Worker boondoggle. At least in that one the workers still got something.
Mind you, not everyone at Bell works for free; CEO George Cope took home over 11 million last year. That's almost a million a month!
C'mon folks, if you can find a million a month for the big cheese, you can find something for these unpaid interns too.
This is the kind of egregious exploitation that gives capitalism a bad name.