Sorry that's untrue. Top companies such as Google, Meta or Microsoft absolutely do not abuse H-1B workers or treat them any different. As I said there may be smaller outfits, or IT shops where this is happening.
Who can we ask to stay late? Who "doesn't mind" 12 hour days? Who "doesn't mind' being on call. Who won't mind if they get a smaller bonus or raise? How about Sandeep who is afraid to say no because if he says no too many times and loses his job him and his entire family have to move back overseas with minimal notice?
That's how real exploitation happens these days. And sometimes even good managers don't realize they're doing it, because, after all, poor Sandeep even said he didn't mind! He's just a really hard worker!