What's the "dodge" here? All these companies already have a large presence in other countries. They can adjust employee counts in each of these locations as they see fit.
Let's say you make companies pay a tax per non-US employee. So they transfer the non-US employees to a contractor, and pay the contractor. This is often the default arrangement anyway. What do you do now?
You would need China-level capital controls to make this work and that is not compatible with the dollar remaining as a reserve currency. Nor will Congress or the Supreme Court go for it.
Yup. This is not difficult and it’s a fairly bounded problem. Only a few hundred companies are capable of the level of outsourcing that is considered significant. And those companies are highly sensitive to regulatory demands
"This is not difficult and it’s a fairly bounded problem"
Epic handwave. And you're wrong btw. If anything small business outsources even more than large companies. Tons of small business owners have zero US employees but have a personal assistant/CX agent in the Philippines, IT contractor in Latam, design contractors in Eastern Europe, etc.