Good for them, but the cynic in me is telling me that tuition will continue to significantly outpace inflation, in part bc of this. $100K/year to attend a prestigious college isn’t far off imo.
For grad students who are serving as teaching assistants or as full "instructors of record," they are still being paid less and given substantially fewer benefits than tenured faculty.
There are many factors driving the increase in the "list price" for undergraduate tuition — I doubt that the take-home pay of grad students and their health insurance are significant factors.
One of the things the union provides is the ability for students to get "student jobs" that are more geared towards entry-level work and easier to get. Almost everyone has these jobs at least over the summer, often also part-time during the school year.
Another big thing the union provides are food coupons so you can get discounted meals at participating restaurants. Fully funded from said tax on student work.
Every once in a while the union organizes protests against tuitions and such.
The biggest outcome is that people choose to be students, at least on paper, until 26 when you age out of benefits. Because the tuition is free and the benefits are amazing.