I think of it as less ironic, and more "There is a union constantly fighting to get Berkeley TAs paid more, and that union is more successful than no union at a

I think of it as less ironic, and more "There is a union constantly fighting to get Berkeley TAs paid more, and that union is more successful than no union at all, so Berkeley TAs are paid more." It's a weird situation, since they are paid better than most TAs, but worse than a computer science instructor with that level of experience generally would be paid.