Unions in the United States are adversarial and corporate. They are institutions and powers in and off themselves, which makes them far different from their generally much less militant European cousins. The adversarial part means much more willingness to engaged in scorched earth outcomes (by both companies and unions). Unions have taken over corporations (United Airlines for example), destroyed corporations (Eastern / National). Unions compete with each other as well.
In my country the unions are fairly well-established and tend to sit across an entire sector, covering all businesses operating in it (workers individually choose whether or not to join, but the company isn't allowed to discriminate either way). Like there will be a Nurses union, a Teachers union, a Public Sector union, a Warehousing and Logistics union, a Port & Dockworkers union, a Retail Workers union... the list goes on. One US example I've heard of like this is in trucking (Teamsters union?), but I know little about the history of US labour relations generally. Could there be an Amazon Workers union that covers an entire state?
Employers of a certain size here are also obliged to provide registered unions with access to business premises, ability to hold certain (non-mandatory) union meetings during work hours, etc. Some industries have upwards of 20-30% of all employees joined to the union, a few even higher.