What is secret about a union? Also the word carries a context, hence the mention of duopoly. So no, not spot on. Also you failed to mention that capital works

What is secret about a union? Also the word carries a context, hence the mention of duopoly. So no, not spot on. Also you failed to mention that capital works to actively disrupt market equilibrium for wages. So by “colluding” the union is merely attempting to counteract that.