I'm sure there are other things that call themselves unions but don't serve the same function we expect of organizations using that word. I'm not really knowledgeable about either of the things you mention, so I don't know if I'd view them as fitting this description or not. Both seem unlikely to have the kind of broad negative impact police unions have, which is particularly egregious because they effectively make public oversight of a government function with a lot of potential to do harm impossible, which has the knock-on effect of making that harm more able to propagate, to the point where it's both quite severe and commonplace