I've experienced both extremes and have mixed feelings about both as a result. Not really pro or anti-union right now because they both have disadvantages.
I worked union up in Minnesota years ago. I worked on a respiratory unit where the respiratory therapists actually had it in their contract that they don't change out suction canisters and that it was a nurses job.
"That's not in my contract" was echoed constantly.
The RN's and LPN's were represented by two different, and often conflicting unions, and as a result, were often pitted against each other.
The RN union was big on this "grid" that was used in staffing patterns. It was designed to keep a certain number of RN's on each unit based on census and was sold to us on the paranoia that LPN's would "take over" because they were cheaper labor if we didn't ensure a certain number of RN's on each unit for each shift. It was very unsafe.
If we had too many LPN's scheduled (more than 2) then we had to swap LPN's for RN's on other units. We often traded out our regular staff acute care, vent trained LPN's for RN's floating from psych and rehab who had never touched a vent in their life.
All for the sake of the almighty "grid" designed to protect RN jobs from LPN's.
Minnesota's attitude in general seemed to be that any RN, regardless of skill level, was always beter than any LPN, and I witnessed with my own eyes that was clearly not true on a respiratory/vent unit.
In addition, I worked with many nurses who should have been fired or even had their license pulled because they were so bad but the union always protected them. The union could protect anyone who could barely, barely meet minimum standards or was able to fake it enough.
Then I moved to Texas where the mere mention of the word union could practically put you in jail.
The RN's, LVN's, and RT's in general seemed to work more as a team without the constant bickering about contracts and stepping on job description toes. The RN's were not paranoid and threatened by LVN's in TX like they were in MN. I liked it at first.
But over the years, I witnessed a lot of administration bullying and running reigns of terror over nurses due to their vulnerability and lack of power as a group.
I saw many careers ruined over the famous "Group One" blacklist that hovers over DFW like a dark, dismal cloud. A supervisor/manager can make up any story about you that suits them and put you on the list, it doesn't need to be substantiated. You then become unemployable by any other hospital in the area and can do basically nothing about it.
I've seen co-workers, patients, and family members make up stories about someone that they simply don't like for one reason or another, and they get fired without any reason or recourse. Your side of the story doesn't have to count for anything.
I've had two co-workers reported to the BNE on completely made up stuff by bullying and terrorizing employers which cost them plenty in legal fees and time along with the fear and anxiety that goes along with your license being reviewed, all because someone decided one day that they don't like you or didn't like the way you talked to them or looked at them.
So what I've taken away from this entire experience in nursing is that when choosing a state or hospital that is either union or non-union, it is simply a matter of picking your poison.