Why? Unions work the best when they are formed around a cause everyone cares about, that is how we got workers right in the first case, there is nothing that says you need to form a union when things are good.
Because at the time you want to form a union due to things being bad, your employer already has the workers in a position of fear and control, and they have reasonably free reign to do whatever they want and toe the line of illegality when it comes to intimidating workers who are discussing unionization.
Talk to a union organizer about this. They'll help you understand how this type of monopsony looks to a worker when they're trying to organize.
