If you can pass a law about wheels only when you've bolted four of them together and attached an engine, can you similarly pass laws about microprocessors once you've attached memory, screen, a wifi link, and a global packet network known as the internet?
"We understand that cars remain cars even if we remove features from them. Cars are special-purpose, at least in comparison to wheels, and all that the addition of a hands-free phone does is add one more feature to an already-specialized technology. There's a heuristic for this: special-purpose technologies are complex, and you can remove features from them without doing fundamental, disfiguring violence to their underlying utility."
Computers and software such as Google and MegaUpload are not special-purpose enough that you can make legislation about their design without "doing fundamental, disfiguring violence to their underlying utility".
So in this analogy, our copyright law is like the laws on cars. We already have laws saying you can't drive cars past the speed limit, or do other various things with them. But we don't have any laws for wheel manufacturers that say that their manufactured wheels cannot be used by someone else in the commission of a crime. Penalizing Google for inadvertently allowing someone to find a page (hosted by a third party) that contains copyrighted content is like fining a wheel manufacturer any time one of their wheels is used as a component of a car that was used to rob a bank. Besides being patently ridiculous, there's no way for a wheel manufacturer to know which cars are going to be used to rob banks.