First, just a general comment: Good companies rarely find their employees searching for a union because they take care of people and communicate often. So the real question is if you are unhappy or have had a rash of bad employers/issues, maybe look at which vertical industry you are in or how you are selecting your next job. Not a dig on you, just something to ponder.

IMO, a union would be the worst thing for our industry and profession. Like someone else pointed out, wages are generally good, benefits are flexible and we have the ability to freely move and negotiate with any employer based on our ability and value. If knowledge workers give up the right to negotiate what is fair and equitable for them and the value they can deliver then you will see a significant number of engineers etc looking for other professions where they can still do that.

I do agree that there are wide ranging salaries/benefits, but it is because people all bring a different skill set, knowledge and capabilities to the table, and not everyone deserves the same pay in what we do. We are not all assembling the same 22 parts on an assembly line with the same training and therefore deserve equal compensation. I will happily pay a software engineer that is super talented and been in the industry for 10 years significantly more than what I would pay someone who has just gone through the motions for the last 10 years and is good but not special. If there was a union though, I wouldn't be able to do that because every person has to fit in a pre-defined box and each person in that role gets x, y and z regardless of their value to the organization. And over the long haul companies generally deteriorate employee morale and benefits even more when a union is introduced, because if it isn't in the union contract it won't happen. There are some pretty awesome exceptions to that rule, but not many.

I have worked in software basically my entire career, and have been at companies that had significant groups of staff unionized, and a few years ago I was contracted to a company that was being unionized for the largest group of staff. I can tell you that employees there were promised a panacea by the unions, and they finally selected one and when negotiations came down to it, the employees lost and now a fair number of them regret it. Others are still fighting saying it was a good thing cause now everything is fair and in writing, but really all they did is take the great employees and force them to fit the mediocre box, and take the bad to mediocre employees and give them a pay and benefit increase. Guess which ones are on which side? I had no stake in that fight, but talked to people about both sides of the coin. Now all discipline is equal and "fair". So real example in their case, a guy that makes a minor non-critical mistake after 20 years of loyal service gets punished equally as the guy who has 1-2 years of service and bad mouths the company at every chance. Is that fair? I don't think so, maybe you do.

To be up front, I generally dislike unions, but feel they did have a place in a previous time when employers abused their employees, and in rare circumstances still do. Please don't get me wrong, people in unions are generally good, hard working people; but I feel the union itself on the other hand is only out for its own interests (not yours) and that means raising dues and collecting more money, which they do by getting higher wages and more retirement benefits etc. Look into unions that your County governments has to deal with, look at the terms in those contracts etc. See what it costs taxpayers. It isn't that the people in the union are undeserving of fair treatment, but look at both sides to see what is reasonable and fair.

TL/DR: Unions generally suck, the stifle employee value and drive costs up on employers.