Doctors also have a union and for the most part aren't making nfl wages.

I don't understand what makes people think that software engineers are so valuable that they'd get wages that are multiples of doctors.

Scarcity is not necessary for leverage. Preventing defectors from collective bargaining is.

The Logic of Collective Action explains the mechanics. https://en.wikipedia.org/wiki/The_Logic_of_Collective_Action

It's basically game theory, by another name.

> Scarcity is not necessary for leverage. Preventing defectors from collective bargaining is.

"Preventing defectors from collective bargaining" is also, more or less, the definition of what an economic cartel does.

Companies are an economic cartel for capital, but we’ve don’t take their existence as a controversy