Japan has one of the oldest populations in the western world. And a lot of their elderly people are dying in car accidents. That means that the advent of autonomous cars might be a good thing for them.
The number one concern regarding autonomous cars in Japan appears to be safety. In 2012, 4,411 people died in car crashes in Japan. 2,264 of the people who died in these crashes were at least 65 years old. In some cases, these people were victims of an accident, but in a number of instinces they were the ones who caused the crash.
Automakers believe that autonomous and semi-autonomous cars will be safer than people driving on their own, and in a lot of cases, I think I agree with them. And since nearly 90 percent of accidents are caused by driver error, taking the driver out of the equation in situations like commuting, traffic, or where the driver just flat out doesn't care should make the roads safer for everyone.