To some, the idea that a self-driving car could take you to the pub and back without worrying about drink driving may seem trivial. But when you look at how many crashes are caused by alcohol, the impact could be huge.
I also think that elimination of drink driving will be one of the strongest drivers of adoption of self-driving cars. Maybe not so much in England, but in many places in the US and Australia that I've lived, driving is the only way to get anywhere, especially at night. The idea of having a car that could take you to the pub and back, letting you drink as much as you want without organising a driver, would be enough to overcome a lot of peoples' aversions to handing over control to a computer.
Obviously you are not allowed to drink and then drive a car. But can you drink and “drive” a self-driving car?