[thelamest]

He's largely taking examples from public-sector unions, which have particularly problematic legal framework in the US.

Private unions can be essentialy seen as corporations, very much like any other firm, that sell labor. Such unions can in principle specialize, compete and offer unique advantages. Again – just like any other market firm. It's just that the US law makes that hard by setting them up for a narrow antagonistic role of fighting with labor management for goodies.