The laws are enforced harshly and consistently, so people follow them. As a result, you have low crime and low total incarceration.

Take auto theft. In California, we have 1 auto theft arrest per 15 stolen cars. Incarceration rate is 1 in 5 of those arrested, so 1 per 75 stolen cars.

Japan has 1 arrest for every 2 stolen cars - A much higher rate of getting caught.

Japan has about 5,000 stolen vehicles nationally per year. California has about 200,000 per year.

As a result, there are very few in prison for it, despite the 10 year sentence.