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.
You have to look harder. It's not always explicit as OP says with threats of deportation. Rather there's a huge power imbalance.
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!
You are right, unless you have been present at every manager-employee interaction you can't say it has "never" happened. But to claim that this is happening requires more than just one or two instances, right?
I used to think the same thing until I was brought in on an important legacy project that put me tangential to the "inner circle" and heard a lot of this kind of thing along with other shady practices like authoring the RFP for the government to publish so that the requirements favored the company.
