I doubt that a union could do much against the alleged toxic aspects of academia that you are pointing out. There’s nothing they can do, for example, to change

I doubt that a union could do much against the alleged toxic aspects of academia that you are pointing out. There’s nothing they can do, for example, to change the fact that tenure track jobs are rare, which is what drives a lot of the stress for grad students. More likely they will be involved in labor disputes involving how much TA work the grad students have to do.