“Unless you are Nielsen Family , it doesn’t matter what you watch.”
Even over cable?
Yes.
Nielsen only gets ratings by their own equipment. And the Networks & their customers accept them. Customers of TV networks are the advertisers. Not viewing public.
You are correct - the set top boxes report back to the mother ship (cable or phone company). The data they capture is more valuable than the ad revenue at this point. And a lot more reliable than Nielsen. And, of course, they are happy to cooperate with the government.