Apart from this, senior union reps and management tend to get cosy and form coalitions against workers and shareholders.
The people that win are the people that are good at politics, workers that are mediocre, and people that are uncomfortable with fast-paced change. Unions are great at slowing things down and keeping things in slow comfort zone so people don't have to learn new things.
Imagine the mediocre 50% of your company gets to determine the processes and procedures used in your team. That's a union shop.
Imagine that manager who isn't very good at his job but is good at politics and that union rep getting drinks after work, and making a coalition against the fast rising manager with aggresive new initiatives in mind ... that's a union shop.
Long term your company will stagnate and die.
Short term, a bunch of mediocre people will feel comfortable.
Flavor of the day workers will get hired based on checking boxes ... not based on any objective criteria/merit. That's a union.
Ever wonder why 90% of cops are white in the Bay Area, even when the neighborhoods are 90% non-white? That's a union.
Unions are the big lie that political animals tell everyone else ... OH JUST GIVE US THE POWER AND WE WILL EMPOWER YOU!
It's only true if you are incapable of providing for yourself. If you have the skills, fight against the union as long as you can, and then leave.
Best decision my parents ever made was to leave the union-choked midwestern city where I was born, to come west thirty years ago. I probably would have been one of those rust-trapped casualties by now if my parents had stayed.