It also doesn't account for the fact that H1B isn't just for engineers. Not all highly skilled professionals get paid salaries commensurate with the IT and CS industries.
So now we also need to split it by job type.
There's a lot of overhead involved in getting this proposal to just be as good as the current system, and even more to make it better. If we do all that, sure. But I'm not sold on the idea that we would.
Some industries don't have the cash flow and ability to pay significantly higher like we have the luxury of in tech.
Even in for-profit industries, margins are not always high enough and competition is often fierce enough that they cannot afford to raise prices to raise salaries.
There are a lot of important industries where margins are quite slim.