"Thousands and thousands" is an exaggeration, particularly considering the portion that is churn between them. There are over 3.87 million software developers in the US[1]. I would be shocked if even 10% of them are employed by the companies you mention Nationwide, let alone just in SV and Seattle. Of that, a minority pull down the massive TC you cite. I think that certainly qualifies as an outlier.

Furthermore, the headcounts of the really big companies, particularly Amazon and Microsoft, are inflated by non-engineers. Citing them doesn't really say much.

[1] https://en.m.wikipedia.org/wiki/Software_engineering_demogra...