The difficulty that the amazon workers face is that they turn up and a screen says pick up these things from these boxes and take them over there, put them in other boxes, stick postage labels on and put it in the back of the truck. It doesn't take much training to do, so workers who unionise are very vulnerable to being fired until enough have joined the union to hold an effective strike.
Unions are always going to naturally form in a pure libertarian society where the only rules are freedom of contract. Usually they are restricted by government regulation.
For example, libertarians do not believe people have a right to food or shelter. You only have a right to keep and use your body and your property.
for example, if you have a scarcity of labor, then labor sets the terms. AI architects could form a union any day they want, they just dont want to.
If you don't like it, you can't pick or make another.
By us law, you are usually allowed to quit the union, if you do, you still have to pay the union part of your salary.
In the US, workers can't join or start a union unless 51% of all workers vote to join them/let them.
If all this sounds crazy, polarizing, and like a recipe for conflict, you are correct. I think the European versions of unions makes much more sense, and are closer to free association
A myth. Employee has leverage.