> Or they can collude with other employers to lower wages (or indirectly, like no-poaching policy, or do what google+apple did with their wage collusion).

You already provided a real world example of them doing it. So it does happen.

And most big companies are now in a phase of buying up disruptive tech companies and extinguishing any competition. That's only going to expand going further. The automotive industry in the US killed public transport to secure their market, they shipped their factories off to other countries, and they still steal subsidies from tax payers.

Tech companies are going to happily follow that path.

> And most big companies are now in a phase of buying up disruptive tech companies and extinguishing any competition

Now? I'm old and have heard that constantly my entire life. It still hasn't happened.

> The automotive industry in the US killed public transport to secure their market

I live in Seattle. The local politicians managed to do that all by themselves.

For example, there once was a car tunnel under the city. The city decided to build another tunnel. What to do with the dug out material, what to do ... I know! let's pack it into the existing tunnel! We spend billions and wind up where we started!

(The rationale was the old tunnel was, well, getting old. Nobody was able to explain why boring a new tunnel was cheaper than shoring up the old one.)

> unless amazon is a monopoly employer, this isn't gonna happen

It's already happening. Various FAANGs have been found red handed signing anti-poaching agreements to lower salaries.