The only place I've worked that locked out any writable device was a place where PID was handled. No one would go through that kind of hassle without needing to.
luckily, we could still charge off the USB ports
In the gaming world you hear of committed players customers spending $100's every month on a fairly rudimentary games as opposed to the $15/month charged by the few remaining subscription games.
or games like Anarchy and Ryzom which are both free, totally, for vary large portion of the game.
the small amount of people who rack up debt to farmville are very odd ducks indeed. I don't think any subscription system would save them from their own madness.
I have a theory that it's impossible to prove anything, but I can't prove it.