You're somehow assuming that forming a union involves forcing everyone to join an organization whose membership is purely voluntary.
> Also, does "no impact" include workers paying extra ~$1000/year in union dues
That's an imaginary number that you made up yourself, and it represents only your own imagination.
> Your comment ignores the other things that workers consider besides wages -- e.g. no jobs.
That's your strawman. You somehow made up this argument that having someone at your side helping you out on your negotiation will somehow force a company to stop hire people to fill the positions they've just opened. Meanwhile, agents are a thing, and having third-party help in your negotiations didn't brought the end to western civilization.