[Ericson2314]

Fairness depends on the ratio of employee employer monopoly power. There may be enough tech companies to form a union, but that just means employees need to be more consolidated to match. Your "fully unionized bargaining" case is just one point in the blanced subspace. A many-to-many relationship where the employers per employee matched the employees per employer (along with other hierarchical symmetries) would be an (outlandish) other such point.