You do not save any money as you cannot pay them less than residents for the same position/ work.
What you get is: One, they usually have the talent they want to bring identified already n(someone who works at Apple in India, for instance)
Two, they get some stability because on those visas it is harder to hop jobs (used to be almost impossible, now it is just harder). But frankly, with Apple in your resume it is not that hard at all.
Breaking news. Foreign labor is cheap when is foreign. In the US (legal) “foreign” labor costs exactly the same as local labor.