Well, theoretically Google employees can Unionize but theoretically Google can also spin out half dozen labs as separate companies and buy technology at exorbitant rates. Meanwhile union employees will get paid union rates which I am thinking won't be too high.
Depends on the deal. My cousin is a state police sergeant. He makes as much as a director level employee in most areas.
My sister in law is a unionized nurse practitioner. Unionization raised her salary a bit, but most importantly stabilized her schedule.
Unions aren't really compatible with the mindset in Tech today, in my experience knowing people. Small movements start, bikeshedding happens, and everything fractures.