How is that even legal and how nvidia gets away with that type of shit?

Companies make unenforceable claims all the time. That's why we've got courts. Theyr'e almost certainly never going to take any one to court, because if they did, it would get tossed out. They can't pull the same "it's a license to a product" bs media services do. Though they still try with the driver. I think for now, they've just run the numbers and figured out it gives them slightly higher datacenter card sales.