Ah, but as a pro-union crowd, you love terms like Teamster, Brotherhood, right?
...the international brotherhood of Teamsters was founded in 1903. The term teamster pre-existed, since the 1840s, referring to people (men usually) who drove teams of horses. And in 1903, it still referred to those people, since motor-powered trucks did not yet exist on a large scale and teams of horses were still used to deliver most goods.
You are probably aware, but, ... "brotherhood" was a self-chosen term, intended to imply mutual support and protection among the members, _against_ the employers. In contrast the demonyms that companies choose are chosen BY the employers, and there is no mutual support intended. In fact many large companies (Amazon, Google) actively resist labor union efforts.
In summary, your comment is sort of off-base for a couple reasons.
and members chose to join that