Why is it important that Google (or any of these large companies) only hire Americans for their jobs in the first place? They are global companies now, they make money from everywhere. Why is the insular "Americans only" idea worthy of consideration at all?
The law forces American corporations to hire Americans, various work visas are exceptions from the law given under certain conditions. It appears the companies are abusing these exceptions and violate these conditions. There is no such thing as a "global company" in the law, with the exception of foreign consulates all the entities that hire people in the US are American corporations.
If your powers of analysis were worth anything you would be running the world not copy-pasting hype straight from CNBC and Big Tech PR
As you are not running the world your analysis is worthless. As such I say; good day, sir.