I don't know how often unions actually impact what the business does instead of how it operates, but here's an example: "Audi's unions demand electric model for main German plant" [0]

> Mosch, who sits on parent VW’s supervisory board, asked top management to provide specific information as to how the growing shift to electric cars and digital services will affect employment at Audi, which has 88,000 workers globally.

Having worked at places where management was deaf to employee concerns about the direction of the business, and seen the consequences of bad management fall upon those employees, I can clearly some sort of leverage would be good for engineers. Perhaps that could involve forcing a company to invest in new technology, thus allowing you to grow as an engineer- and perhaps making your job more secure by making the business more competitive.

[0] https://news.ycombinator.com/item?id=13986889