That is the problem, you can't say being a union will be better. Like anything, you need a good union, that understands the company, and its restraints on ability to pay, along with the ability to look out for good employees (while being flexible to get rid of the bad ones).I wish there was a new version of unionization. The one time I worked at a union facility it was pretty standard for the company to simply refuse to do things for the benefit of the employees and just say "talk to your union, what you have is what your union agreed to." It gave them an easy out where in non-union companies the employees can put the pressure directly onto the employer and the employer didn't have a scape goat. Now the union at that place was weak and run by buffoons which was likely a big part of what sucked about it. So I don't really know, in my experience I'd rather have no union than an incompetent one.
My biggest issue with unions, is the protection afforded to employees who should be fired. This same methodology tends to make promotions more difficult as well, which keeps the best employees held back, and potentially paid less, so the poor performers get their negotiated wage and benefit. Similarly, seniority tends to influence benefits, so a rising star gets held back, and likely leaves. Not to mention the internal union politics. This is the crap that holds companies back.
I'm sure everyone has had horrible teachers with protection afforded by the teacher's union, schools basically can't get rid of them. And the police unions do the same thing.
I'm all for collective bargaining and negotiating fair wages (Hostess is an example of a union failing the employees in this regard), but I also think all employees should be accountable, and if you aren't good at what you do, promotions/raises should not be a given, and it should be easier for you to lose your job if you aren't meeting reasonable set standards. The union should ensure those steps are followed, not protect employees no matter what.
I don't want to work with people that have less accountability, and I wouldn't want to own a business where I have to keep people on like that.
There are definitely good unions out there, that have a good balance. There are also many unions that are awful, so I agree with @Gameface and his view, and expound on it.
A good union will enhance the best qualities of its workforce and take care of its employees, a bad union will do the opposite.
This isn't anything unique. There are many companies that are non-union that do an amazing job taking care of employees in all facets. Unfortunately, there are many that do not.