The companies compete for workers, especially highly skilled ones. One company rising wages would push others to react in a similar way assuming they compete for the same talent.
https://www.cnet.com/tech/tech-industry/apple-google-others-...
I personally think a model like this is pretty fair, if somebody is making 50k a year then pulling in 1M annual is pretty silly - but it makes sense to account for that difference with taxation rather than the arbitrary choices of private employers.