So, when company, factory owner, or who sell service/good get together, and talk how much they will charge consumer, it is price fixing.
So, I just thinking, worker are those who sell larbor. Worker band together, which we call worker union, to decide how much they should ask from their employer, seem similar to price fixing.
Price fixing is a problem because of the power imbalance between businesses selling products, and individual consumers that need to buy them.
Worker unions are a solution to that power imbalance.