Clearly, since so many people drive like the woman in the above photo (Is that a freaking laptop lady? Jesus!), with our without autonomous technology, Volvo's thinking that taking the human element out of the daily driving equation is the best way to hit its goal. So how does the Volvo system work?
Well, there are a lot of sensors doing a lot of different things in a lot of different ways. More on that in a second, but the crucial point here is that Volvo's engineers are approaching the system much like aircraft engineers. When one system fails, there's at least one other redundant system to back it up, so that only the most catastrophic of events will result in failure.