Nope, a sector based union have far, far more power and resources than a site or company based union, simply due to having far more members.
One of my favourite unions stories was when Toys 'R Us wanted to get into the Swedish market.
First of all, you might not realize it, but Sweden has a highly unregulated labour market, we have no minimum wage and the government doesn’t really interfere in the labour market.
Our system is based on our strong unions negotiating with employers and employer organizations.
The vast majority of medium and large workplaces have signed collective bargaining agreements with the largest unions, for the most part it is a formality, but a very important one, with consequences if the parties fail to come to an agreement. There have been several times with large strikes, that closed or severely reduced services due to this, these negotiations and especially the strikes does show up on the national news.
Anyway, Toys 'R Us refused to sign a CBA with the store workers union, and hired staff that wasn’t in a union instead, this is allowed, so the union called a strike against TRU.
Well, other unions saw this and wasn’t happy, and started sympathy strikes, the transport workers union refused to deliver goods to TRU stores, the financial workers union refused to process payments for TRU, the printer workers union refused to print materials for TRU and do on.
All of this successfully pushed TRU back to the negotiation table, and finally got them to sign a CBA.
As soon as that was done, the sympathy strikes ended.
Isn’t that a pre requisite for their job?