That if unionization is so cleary net positive for most workplaces, then it wouldn’t need any sustained agitation campaigns in the first place.
As any company that unionizes would near automatically gain a huge competitive advantage.
> As any company that unionizes would near automatically gain a huge competitive advantage.
No, your "observation" has a fundamental flaw: There's no general "net positive for most workplaces," because different groups have different interests.
Unionization is a "net negative" for certain groups (managers, owners) and a "net positive" for others (employees, if done right). That's why there are sustained agitation campaigns against it.
Add on top of that that a largish number of managers just plain suck at their job, so being in a union can be useful to push back against either lazy or incompetent managers.
Because there are far more people who leave their manager than leave their job.
Every single worker is ultimately disposable. If you think your employer is disposable to you, that's not because you're special but because so far you've been extremely lucky. It is far easier for a company to replace a worker than it is for a worker to replace the company they work for - we just tend to see the "inability to find a new job" as a personal failure (i.e. bad performance at the job of "finding a job") whereas we take the existence of job vacancies for granted as a normal part of the market and maybe even a positive indicator for "growth" (which we define as desirable even if it's artificial or unsustainable).
By definition with sufficiently seperate interests, then anything (or nothing) goes.
Maybe not 100% of the time in 100% of societies, but certainly more than zero in every society I’ve ever heard of.