Current tech doesn't work in rain or snow. Computer vision cannot tell if a car is moving behind a bush, or if it's a bird or a plastic bag. It doesn't work off-road. These issues, and many others, will take a lot more than 10 years to fix. There is also no guarantee that Google will profit from driverless cars when they do arrive. The whole driverless car project is simply a way for Google to distract investors, the press, and the public from the lack of ideas in their core search and advertising business.