Not knowing what country you are in, I would bet that the situation of unions there ultimately is a result of the global labor movement of the 19th and 20th centuries, which came to be via strikes and grassroots union organizing activities.
Of course, yes, I am trying to say that what you are describing as US-style unionization is closer to how unions have historically worked. It would be your country's situation that is exceptional, because apparently workers there have won so much power, that militant/grassroots organizing is less necessary.