You're the one who doesn't understand the free market. Grad students tend to be intelligent capable people (from privileged backgrounds too!). Therefore we do

You're the one who doesn't understand the free market. Grad students tend to be intelligent capable people (from privileged backgrounds too!). Therefore we don't expect grad students to be desparate, because we infer that they ahve a lot of other options. The only sense in which grad students are desperate, is that they really want the other advantages that being a grad student confers, most of all the education and experience, and the degree they get at the end. And this was precisely the point of the post you replied to: graduate students are getting non-monetary compensation. If you disagree, I challenge you to find one testimonial from a grad student whose story is that they were so desperate for money, that they had no choice but to enroll in grad school to make ends meet.