I will offer an opinion as a staunchly anti-union person, so that you can get a feel for the perspective.
If working conditions and pay suck, I much prefer a UBI so people can work less. It has none of the downsides of the below.
- I want my underperforming colleagues to be fired quickly. It's unfair and annoying that laggards are protected and free riding off their colleagues' (my) effort, and it leads to ineffective orgs.
- I don't want seniority or rank to be rewarded. It's unfair to young people (me) who are more competent and ambitious, and it leads to ineffective orgs.
- I want to negotiate individually because I believe I will make more money as an outperformer. I don't want a centralized handicapper to blunt my compensation.
- I don't like that unions are rent seeking in nature.
- I don't like that unions often are exploited by organized crime.
- I don't like that unions interfere in the broader political process and democracy via activism and political pressure (e.g look at the fact that the new EV subsidies will be going to everyone except Tesla, it's a perversion).
- I think people should be free to organize, but I don't like that the state grants special asymmetric powers to unions.
- I don't like especially public sector unions that I believe are doing significant damage to society broadly. For example police unions that shielded Chauvin after a large number of complaints.