In most cases here unions are fairly large organizations where the larger union covers dozens or hundreds of companies. So it wouldn’t be like ‘Bob’s maintenance shop union’ it would be like ‘international brotherhood of machinists union chapter #1234’.
And when that is done, the relationship between the workers and the company changes. The union will negotiate a specific contract with the company which all workers and all jobs then are covered under. This provides a lot stronger protections for the workers, but can also be less flexible in some cases. And of course the worker has to pay dues to the union, it’s usually not that much but it’s not zero.
Point is, if the workers are happy and have good relations with management then they often see no reason to go through all this.
On the other hand when management starts turning the screws and tries to make more profit out of the worker compensation, then it’s absolutely time to unionize and workers are even more seeing that.
The problem is it’s not just ‘form a union’. In most cases unionizing means joining a much larger union that covers many hundreds of companies. And it will mean that all questions of compensation or discipline then have to go through a union contract. It means more paperwork and less flexibility.
If there is trust between workers and management, then workers often don’t see much benefit to going through all this. And that’s why the guy said every shop that went Union deserved it, because those shots all tried to save money by screwing their employees and so the employees fought back and unionized which ended up costing the company more than if they had just paid the workers correctly in the first place.