I have no problem with unions and I'm extremely pro-union. I'm also practical and not naive enough to think that you can join a union in every job. They don't exist for a lot of jobs at all and you have to be very diligent to be able to form one without losing your job from unjustly being fired.
What I hate is people giving shitty advice so they can feel superior. "Join a union" is great advice if your job/field already has one. "Join a union" when someone has a work dispute with their clearly non-union employer is idiocy and belittling to the person that is asking the question. I made the analogy above, so I'll turn your question on its head, do you think depressed people should just try to be happy? Because it's the same level of advice as, "Join a union" in this instance.
It's really not even advice. It's just self aggrandizement and dumbass people looking for a circle jerk to join. It doesn't address the issue that OP has in the slightest practical way, and is kind of callus to their actual problem.