My good friend Gary Fouse out in Orange County, California, has asked me to acknowledge the negative impact of unions. He likes to focus on thuggery, which in my opinion is a bit misplaced. But a more mundane problem is that traditional union work rules can indeed deny individual workers flexibility they really would prefer to have, and also interfere with legitimate managerial initiatives.
There is a reason for traditional union work rules. About two hundred years ago, production which had been performed by independent crafts men (they were almost all men) was taken over by the rise of large industrial enterprises. The new methods produced far more, with less labor per item, making all kinds of goods available at a lower cost. In the long run, it contributed to general prosperity. Sort of.
Both the craftsmen newly rendered into wage laborers, and the gentlemen investors inventing the role of employers of large scale wage labor teams, looked to existing law and social custom to define their roles. Craftsmen demanded autonomy, and respect for their craft. Employers, who thought of themselves as MASTERS, tried to treat their employees as dependents and inferiors, albeit sometimes with a certain paternal noblesse oblige.
When adult citizens need to "get a job" to support themselves and their families, while a smaller number of adult citizens possess the wealth to invest capital, and the power to hire and fire, equal citizenship ceases to exist. When discretion is left up to owners and managers, it can and will be abused. Even seemingly reasonable decisions will be made according to the best interests of management, ignoring the best interests, or even the necessities, of employees.
A good example: a mother whose child is sick must take them to the hospital or the doctor. But, an employer who needs employees to be at work, on time, every day, simply cannot accommodate that, or won't. The operator of a pumpkin farm entertaining tours of school children might tell the secretary to go home until her child is well, and cover the post. The manager of a transport company might callously issue a final written warning.
Standardized union work rules define a baseline of rights that an employee is entitled to. Seniority isn't a great way to promote, but if "merit" or "talent" are the basis of promotion, the boss will decide what they want to recognize at "merit." It may be the brown-noser who gets the raise, or keeps their job during a lay-off, or the female employee who is willing to put out. To this day, in most states, absent specific legislation or union contract, a wage employee can be fired "for any reason or no reason." It's called "employment at will."
But if a way could be found to limit arbitrary and capricious action by management, while also allowing flexibility to both worker and owner, it could be a big improvement. Unfortunately, anything left up to the "choice" of a woman or man who "needs a job" can be quickly turned into "voluntarily agree to this, or we will not hire / will fire you."