Counterintuitively, Unions in the US have much more legal power in some ways than international counterparts - if they get officially recognized.
But official recognition is only workplace-to-workplace and has an election process to follow:
https://www.nlrb.gov/about-nlrb/what-we-do/conduct-elections
Since it's more all-or-nothing per workplace, your membership is basically tied to the shop. And for some of these newer workplaces, they might not want the baggage that comes with some of the older unions.
Some US unions work on a "hiring hall" model where your membership is not tied to a workplace. This includes electricians and plumbers and other tradespeople. And also actors and writers. But you cannot just join them if you want to. Generally you have to follow a several-year application or apprenticeship system.
It would be really hard to do sectoral bargaining in the US because there are vastly different costs of living across the country but each state is required to have free trade with each other. So to have New York workers bargaining for Alabama workers or vis versa would be a disaster.
It should also be worth pointing out that countries with sectoral bargaining also have huge number of self-employed and sole enterprise people. France has something like 2-3 times the number of self-employed people, and my understanding is that it's one of the only ways people in these economies can "opt-out" of bargaining agreements.
You can go to a union's homepage and click "JOIN TODAY!" if you wish. It just doesn't create any obligation for your employer to care.
Not true for Norway, at least.
Edit: although I'm in tech I understand it covers everyone regardless of role
- Your union is likely to negotiate salaries and benefits with the umbrella organization that the employer is part of. Strikes are usually some employees across a range of companies, rather than everyone at a single company.
- If not, then the union can help you negotiate.
- The union will give you legal aid if needed, whether it's advisory or for a court battle. We have very strong worker's rights, but sometimes companies try to bend the rules.
- The union will arrange relevant seminars, courses etc. which are usually pretty cheap.
- Several parts of the Working Environment Act only apply to workers whose unions have agreements (tariffavtale) with the employer. For example, if you have such an agreement you're entitled to 5 weeks of vacation instead of just 4 weeks and 1 day.
https://lovdata.no/dokument/NLE/lov/2005-06-17-62
But most of this is moot, since many employees in most companies are organized anyway. Like all civilized countries, unionizing is a right.
https://en.wikipedia.org/wiki/European_Convention_on_Human_R...
Also usually when you hear that some group has 'formed their own union' they're still affiliating with an existing Union take the recently formed VFX Union, they're affiliated with IATSE.
Some sectors do not have sectoral bargaining but certain unions have agreements with some subset of employers in that sector to have all their workers covered by any deal that is struck. The incentive for employers in those sectors (i.e. automotive) to join these agreements is that desirable employees usually prefer unionized shops, as they have better overall compensation packages and perks. Also they might not want to become the target of strikes.
Not directly tied to unionization, workers in companies above a certain size have to be included in decision making (i.e. in public companies worker representatives get board seats) so a pro-union position often has a certain groundswell of support within a shop.
For historic reasons, in some sectors union membership is part of the "culture", as well. Historically, unions have had an important role in upwards social mobility, popular education, culture, etc.
In most other countries, before that point workers can still be union members “at large” get support from members in other workplaces and from the central union in their quest to gain recognition in their workplace.
The IWW is an example of a union that accepts members from non-union shops both in the US and many other countries.