We all know how that works - unions increase wages and benefits, if the school has a hard cap on the dollars it has to engage fewer grads. In addition, we have all seen the aged grad student - 6 years on his PhD, with a union, he does not care - he has seniority.
I could go on. In essence a grad school is a golden opportunity to advance your self in leading institutions - why hurt it?
I disagree. The other thing unions create are standard working conditions. Some supervisors/departments are terrible - even within the same dept/uni.
Grad school isn't about the money but it is all about the supervisor/student relationship. The power imbalance is extreme and sits with the supervisor - a 6 year PhD is not something most people want, they want to graduate and earn some $$, but another year can generate a couple extra papers for the supervisor...
I think that somehow correcting the power imbalance is the key to improving the lives of grad students. In most normal jobs, if your boss is a jerk, you typically have the ability to leave and go somewhere else, and quite possibly end up better compensated as a result. It is exceedingly difficult to switch phd advisors, especially without sustaining a significant setback in your graduate career. I believe this one of the leading factors in exploitive advisor-grad relationships.
True enough, the bad marriages do exist, tenured dogs can make life hard for their undergrads and post docs, but new tenured positions are getting rarer as old ones die off.
