I'm only going to say it once, because I have no doubt I'll encounter the same uncivil behavior you did, Paul. But there are indeed problems with unions in many cases.
While there are good
individuals in unions, as organizations, I think they are mostly corrupt in the leadership, partly on purpose and partly due to unfortunate, unintended consequences. Some things, I think, began with good intentions and in their day, accomplished a lot, but when you take away incentive-based pay (versus seniority-based pay) and make it damn near impossible to fire people who don't perform, what incentive is there to excel? This is very similar to what you often see in government workers, who are under a similar pay structure.
I've seen the devastation brought on by unions, when they get so powerful that they get a chokehold on the companies they spring up in that they end up driving said companies out of business or, unfortunately, overseas. (Or, if we're more fortunate than that, to a right-to-work state.) Entire towns are economically destroyed because of short-term greed on the part of union leaders that failed to consider the cooperation necessary for long-term survival of the entire company, of which the employees are the part. In other words, what should be a symbiotic relationship--and what I think was originally intended to be one by the first founders of unions--becomes parasitic and consumes the host.
As far as the important part of the role unions once played, such as getting needed safety legislation into place, overtime legislation, and required meal breaks, as much as I distrust the government, the legal framework in place does seem to serve reasonably well. I do not work for a unionized company, but feel that were there an incident that jeopardized me in any way, the state and federal government would offer sufficient avenues for recourse. Nor am I some poor, abused peon just because I don't have a union rep.

(Indeed, I think the relationship I have with my superiors is better because I can approach them and have an actual conversation that isn't constantly filled with implicit threats from a union.)
Overall...I'd say that aside from some extraordinary circumstances, such as extremely dangerous jobs, where extra vigilance is required to protect life and limb, unions have outlived their usefulness.