Comment Sorry, but... (Score 1) 334
Your problem is one of social engineering, not hardware or software. It's almost impossible to "idiot-proof" any kind of technology if the people using it absolutely refuse to learn. Sadly, this seems to be your problem.
Until your relatives can be persuaded that the device in their house can take their identities, their life savings and perhaps even their children, they'll just keep going merrily along, trusting other people to clean up after them.