Or maybe its all nonsense because repeatedly people in the US have shown a susceptibility to propaganda and a willingness to vote against their own best interest? Or for that matter to vote for politicians that refuse to take stances which deviate from the party talking points.
Fundamentally, the us government is there to represent the interests of the citizens. Or if you go back far enough the states, which in turn are there for the citizens. Unless you buy into the idea that really the representative nature of the government is to represent the interests of the wealth elite and make it appear that the people have a say by electing their representatives. Something that I think the 17th amendment/etc tries to clear up...
Labor unions are there to represent the interests of labor.
Given that the majority of voting age people in the us, fall into the labor category there is a fairly large crossover of common interests between labor unions and general government when it comes to economic issues.
As I mention in my cousin-comment, our system is set up to reward those who can organize, which the wealthy elite and large corporations are much better at than the population of individuals with divisive identity politics being shoved down their throats by PR companies. Breaking people's ability to organize is why there is such a push to convince us that trade unions are evil.
Unions are a response to a shitty situation, and they have flaws. Not having unions, in the face of dwindling individual share in a growing economy, that's even worse.