depends on the field

but its a bad and outdated assumption to make, at least for tech

department of labor forces companies to submit compensation data

someone aggregates this on h1bdata.info

(the data is not uniform though, as some companies are including total compensation and this is normalized as “salary”)

In tech? Absolutely.

They earn above the tech average wage, or they earn above average wage in the country? If they work in tech, but earn below the average tech wage, then they’d actually be bringing the average wage down when you consider the opportunity cost.