I think the university ecosystem should have discussions about that, because the support for graduate students is a combined approach, as my colleague Ted Hewitt mentioned before. A rarity is a student supported just by tri-council. It could also be teaching assistantships and funds from provincial and private donors.
What is the acceptable minimum wage for a graduate student at a university in a big city? That's something I think universities should address. There's also the element of tuition and how that factors in.