The cynicism is based on decades of the anti-union rhetoric of plutocratic pols and pundits being blared loudly about in the U.S. main stream media. Unions=Corruption and Socializms! Commiez! has become an ingrained cultural/political backdrop "fact".
Other than a few high profile cases of union leadership corruption brought to light back in the sixties and seventies, unions back then and now have been remarkably low-key, and corporate directors traditionally saw them as a type of partner in labor efficiency management. They do, indeed, strongly express an authoritarian corporate mentality in regards to their worker members because of using full time professional reps. Not surprising. Very unfortunate, compared to the European modus.
The European labor unions have such deep, strong cultural roots in the ancient tradition of guilds, and are so common, appreciated, and well-understood by the general population, that most pols would never dare suggest outright dismantling any of them, or demonize trade unions in general as they do with impunity here.