This is the reason it is hard for me to relate, as I have been legitimately poor and 15,000 seriously seems like a significant amount to me to live on which may be hard to relate to. This is what it comes down to; perspective on what is fair and what is not.
My dad lives on disability, and I have experienced living in legitimate (though not abject) poverty. I appreciate your view, and I think I share it to a certain extent. I lived on my own when I was 15, paying for my expenses with a part-time job.
I was also pretty surprised with the $15 000 number when I arrived. This was before I really knew what a PhD entailed (or what the cost of living in Toronto was!). For example, some amount of conference travel is essential, and while your advisor will (usually) pick up some of the tab you still have significant costs in this regard.
Maybe it would also help thinking about this in terms of grad students getting a living wage does not mean that other groups should not also get a living wage. Personally, I feel like if you're doing something (anything) of value full-time, you should be compensated at least enough to have a (not-overly comfortable) life. It doesn't matter if you're a researcher, an assembly line worker, a chef or a door-to-door salesperson; if that's what you do, you should be able to live your life.
How do you feel about solutions like investments in graduate housing?
This is certainly a step in the right direction. I think the membership of the union wants more systemic solutions though.
I don't mind so much specific targeted funds to those in most need, like tuition waivers/reductions for 5th year+ students. In some ways that is preferable to across the board increases in the minimum.
Sidenote, I am friends with quite a few chefs... their apprenticeship is one of the most horrifyingly terrible things I have ever heard of.
Interesting! I picked Chef and clinical Psychologist because I also know a few. Their experiences weren't the sort of living hell you described.