I am not against Unionizing "per se" but the role of Unions has never been "tell the management how to run their business". There has been some cases of (smallish) company being "acquired" by their own workforce, and the Unions might have helped with formalizing the deal, but this is rare, and anyway happens only when the company goes bankrupt or decides to shut down.
So I do not understand exactly what you mean here.
A Union can organize and sustain a strike. But they cannot "toss leadership out". Not the CEO, the Board or any manager at any level.
They could theorethically "blackmail" a company saying "strike will not end until X is fired" where X is a PM or manager or whatever but I never really heard of anyone trying this tactic, not to say actually succeed...
Some of that is indeed earned by the businesses reputation, but ultimately this is what I think spurred the decline of union membership in the US because businesses don’t get a lot if any value out of having a union around and the organized workers often find the benefits stagnant after some time
https://en.m.wikipedia.org/wiki/Carry_On_at_Your_Convenience