Hi, I'm scott!
First, I need to state that I am licensed in California only, and that lawyers in this forum cannot give specific legal advice to specific legal problem, but can only address legal issue generally.
With that in mind, I hope I can provide a little perspective: before becoming a lawyer, I served as a shop steward at a major company, so I have those two perspectives to offer.
As a union member, it is easy to feel one is being exploited in many ways not only by the employer, but also by the union itself! Union shop members should keep in mind that in any individual contract negotiation the union fits that into its overall industry labor strategy. And conflicts often creep in with that overall strategy and the specific needs of the individual shop with contract under negotiations.
As you also noted, local union shop officials are also employees and also have their own agenda that may present a conflict of interest. But while not illegal, there may be union bylaws or policies being violated by the use of individuals with such conflicts, and formal complaints to the union can be made.
Shop member can organize and withdraw from the union and create their own mini-union to bargain directly with management -- but obviously that is expensive and time consuming (and why labor turns to unions in the first place!)
Turning to collective bargaining laws, policy and remedies...
to say that collective bargaining labor law is complicated would be understatement.
At the most basic level, collective bargaining agreements ARE contracts that have to be adhered to by all parties: failure to do so by any one party may give rise to a breach of contract. So if a contract commision structure is not being implemented or followed, than a remedy may be available. But because these contracts are so complicated, the parties usually determine it is most efficient to work out the problem among themselves. If any of the parties go to court, they will find the court reluctant to get entangled, and likely to first order the parties to try mediation, arbitration and settlement before they can proceed with a court action.
With respect to the injuries suffered by employees in the broad scenario described -- I'm not sure whether the remedy sought is preferred from the employer or from the union itself.
If there is any tort cause of action, the only one I can perceive against either might be negligent infliction of emotional distress.
But I've never heard of such a tort action against a union, and in any case it would be difficult to substantiate. This cause requires the offending party to be away of the potential consequence of their behavior, and be aware of the vulnerability of the victims, and there must be demonstrable physical impact from the mental distress: mental or physical health care necessitated by the distress, for example.
Also, with respect to the union and this cause of action, it will likely argue that by joining and participating in the union, employee-members agreed to allow the union to represent them and bargain for them with tactics at the discretion of the union officials, and so the union members thereby waived their right to bring an action based on an unintended tort such as negligence.
This issue would require detailed legal research and analysis project (I do such research for $30 per hour).
With respect to whether this could qualify as a class action, the first thing to note is that, in general, courts do not like class actions, and strictly construe the requirements for certifying them. There have been class actions certified with as few as several dozen members, but those are older and rare, and now, the general rule is that at least hundreds of class members are needed -- with thousands of class members being preferred.
I know this response was broad brush, and not what you were hoping to hear: we all like clean and simple answers, but the complications in collective bargain labor disputes make detailed answers here impossible. And as I indicated, lawyers in this forum cannot give specific legal advice to specific legal problems.
However, if you found this at all responsive/informative, I would appreciate your acceptance and positive rating.