Okay real talk. I consider virtually all unions* in the US to be yellow unions. They are like that because, during the 20th century, all socialist/communist leadership was purged from organized labor. The unions were made into virulently anti-communist ones, for the purposes of the Cold War, but also for the purposes of declawing the labor movement. As a result, the unions don’t really work to develop class consciousness among the rank & file. And of course they don’t, because union leadership is in partnership with the capitalist class instead of antagonistic toward them. So the leadership is mostly aligned with the Democratic party and that party’s donor class, while the rank & file, having no class theory, are left susceptible to all manner of charlatanry.

(Things are worse still, if I get into labor aristocracy in the imperial core, but I’ll leave it at that.)

*One notable exception is the IWW.