Kevin Drum wonders, absent strong labor unions, "where does the backing come from to pass legislation that would weaken corporate interests?"
This kind of thinking always strikes me as oddly indifferent to the practical question of how concrete political issues work. Think back to June of 2011 when the Obama administration was trying to tackle corporate interests by promoting the elimination of a tax subsidiy for corporate jets as a deficit-fighting measure. Guess who didn't like that idea? Corporate America. But guess which corporations especially didn't like it? The ones who build corporate jets. And guess who agreed with the owners and managers of firms that make corporate jets about the desirability of subsidies for making corporate jets? The labor union that represents the workers.
As the great metaphysician Mitt Romney put it, corporations are people and concrete political controversies often pit the interests of entire firms or sectors against those of others. This reality is somewhat obscured from view precisely by the fact that labor unions are so weak in the American private sector. But if there were a labor union representing the majority of rank-and-file insurance company workers, they'd have been leading the charge against the public option. The United Mine Workers stand up for the interests of mine workers versus mine owners, but also for the interests of the mining industry versus the broader public interest in preventing the coal industry from sapping the atmosphere's ability to absord CO2 emissions.
I think the practical issue here is a very real, but substantially narrower one. Labor unions are a clear and consistent voice for progressive taxation and public services against high-income individuals' strong interest in paying less taxes.
That's a big deal. But the practical dynamics of counterveiling forces in American politics are much more likely to pit sector against sector than "corporate interests" against labor.
UPDATE: To give another example, this time where I thought the labor/corporate combo was on the right side of the issue and the progressive cw was wrong the dread "pink slime" was produced largely in unionized plants by workers represented by the UFCW. When this issue was in the news the UFCW naturally stood shoulder to shoulder with their slime-making corporate overlords since their workers didn't want to lose their jobs.