The power of universities over the lives of grad students really is a problem. TAing (or RAing) is not like other forms of employment where employees are, theoretically, free to leave if they are unhappy with their wages or benefits. Usually, TAing/RAing is an expected part of a grad student’s CV. A grad student cannot simply opt out of these duties — at least not if he or she wants future career prospects. And “job searching” among universities is impossible since University X isn’t going to hire grad students from University Y to TA for it. As long as a student remains in a particular university’s grad program (which, unless she leaves her field entirely, she probably will for 4–8 years, transfers between grad schools being uncommon), she is stuck with any changes the university deigns to make to the terms of her employment, salary and wages included.
Also, the change to a “mentored teaching experience” is ridiculous. Internships don’t last for years on end. And is this institution really arguing that it gives money to “mentees” because it’s feeling generous, but the mentees in no way *earned* this money. Y’know, the money that non-mentee grad students don’t receive?