The fact that "shitty unions are shitty" implies that unions represent both cost and risk that must be weighed against current and potential future states-of-affair. Those who have experienced the downsides of those costs and risks are informed by those experiences and unsurprisingly more likely to be cautious about unions in the future.
I don't necessarily disagree with what you are saying, I do think your perspective is somehwat wrong however. The ultimate goal of a union is of course to improve the state of affairs. But the larger reason reason to have a union is because it is a right to be able to affect your own future.
There are shitty unions, but there are also shitty companies and you only have the right to affect one. If people say shitty things, should you abandon free speech or should you engage in the free speech you believe in? Most people would say the latter because they think free speech is an important right. I guess a similar conclusion would be that worker participation is too important to be left to shitty unions.
I would expect a new union to design around some of the pitfalls that have affected unions past.
Your general attitude sounds defeatist and strange on a community that is all about improving from past mistakes and learning to build better systems by breaking existing ones.
