Ordinarily I'd take the side of labor. But there could exist times when unions make unreasonable/unfair demands. So - when those happen, then I'd take the side of management for outlasting the union.
Not trying to necessarily argue or strawman, just want to point out that the only time I’m aware of (though likely not the only time in general) this happening is police unions. The first one started in the Pacific Northwest, and used their power and leverage to keep the union alive. At a city meeting, the iirc chief put a Manila envelope down for each city board member with their photo and personal information inside - address, family, etc, and put his gun down on top of one. The city decided not to disband the union.
Memory is a bit hazy but I think they did disband it once before then and the ex-cops were such a nuisance that the city went back on it.
I’m doing a poor job of explaining, and the Behind the Police series does much better - the point is, this is my most notable example of a union getting too powerful but quite frankly there isn’t much we can do about it.