I've worked at Google and Amazon. Both paid H-1B less than their american counterparts. In particular because the H-1B workers didn't jump companies as frequent.
All H1B salaries are posted online. First of thats the law.
Google , Facebook etc all post salaries of every H1B application. The salaries are always in top 5% of Software engineering salaries.
You are making stuff up or ignorant of H1B process.