Social security systems in most of the world have been widely investigated multiple times and the case of what OP called "ghost names" ok is nearly non existent. Turns out governments these days have good ways to track their population's life statusb especially when they are being given money. Once someone dies their social accounts get called into question and automatically terminated.

Therefore some serious crime would have to be committed by a third party to keep receiving payments. Body being hidden, identity fraud and lack of investigation by local authorities. An in person check at a persn's residence would not be that hard. These cases are nearly non existent because this is a fraud too hard and risky to execute for just a monthly payment of a few bucks.