Malware tends to be pretty smart and there’s a good chance that there wouldn’t be anything to uninstall, and even if there was, it would be superfluous. Would you really want to announce how to remove your product? The same for a rollback, malware tends to infect the restore files as well, so you can roll back to when your computer was first installed and it would still be there. Then there’s the fact of the interconnected processes which make it extremely difficult to remove. You have self contained .exe’s, you have .dll’s that run as services, you have services that start up with windows, you have startup scripts that reassert links and maintain the infection, you have registry entries that keep reactivating disabled services, you have memory resident processes that detect changes and correct them after, each one will correct for the other if one goes down, it’s like a game of whack’a’mole, there are only two ways to win, take them all out at the same time (very hard), or don’t get infected in the first place.
The thing with these scams is that people are too trusting and have no common sense. If you wake up in the morning to find a tradesman in your kitchen saying that all your wiring is illegal/broken; you have a hole in your roof; your bathroom leaks; your house doesn’t follow building regulations and standards; your door locks and double glazing are inadequate; and that he can fix all of it for you for a fee – you’ll be asking what the hell you had the night before and calling the police. If you have software magically appear on your system without your knowing, telling you that your hard drive is on the point of failure, there are 122 viruses, your security has been compromised and that this can all be fixed in 30secs with your creditcard, do you really believe what it’s saying and fork over the cash, or call an authority you actually know and trust? (I hate 3am panic calls from friends and family.)
Now apply this to the phone, you get a call from a windows salesman saying that your double glazing is inadequate, insecure and revealing personal information about you and it can all be fixed if you let this guy called Barry into your house with his mate, Patch. Barry and Patch walk in, make themselves at home, tut profusely and then give you a quote for an obscene amount, you say no, they leave, and every 10 mins you find them in your living room again, giving you this quote, haunting you until you move house, redecorate, or pay them – until they ask for more.
You wouldn’t do it with your house or even your car, so why let them do it with your PC? They joys of psychology and lack of common sense.