Culture and economics.
Ghana is a nation 95% blacks and has lower crime than Japan.
http://www-rohan.sdsu.edu/faculty/rw...ica/ghana.html
The crime rate in Ghana is very low compared to industrialized countries. An analysis was done using INTERPOL data for Ghana. For purpose of comparison, data were drawn for the seven offenses used to compute the United States FBI's index of crime. Index offenses include murder, forcible rape, robbery, aggravated assault, burglary, larceny, and motor vehicle theft. The combined total of these offenses constitutes the Index used for trend calculation purposes. Ghana will be compared with Japan (country with a low crime rate) and USA (country with a high crime rate). According to the INTERPOL data, for murder, the rate per 100,000 population in 2000 was 2.48 for Ghana, 1.10 for Japan, and 5.51 for USA. For rape, the rate in 2000 was 6.85 for Ghana, compared with 1.78 for Japan and 32.05 for USA. For robbery, the rate in 2000 was 2.15 for Ghana, 4.08 for Japan, and 144.92 for USA. For aggravated assault, the rate in 2000 was 448.42 for Ghana, 23.78 for Japan, and 323.62 for USA. For burglary, the rate in 2000 was 1.3 for Ghana, 233.60 for Japan, and 728.42 for USA. The rate of larceny for 2000 was 0.08 for Ghana, 1401.26 for Japan, and 2475.27 for USA. The rate for motor vehicle theft in 2000 was not reported for Ghana.
The rate for all index offenses combined was 461.28 for Ghana, compared with 1709.88 for Japan and 4123.97 for USA (noting that motor vehicle theft was omitted as part of this total for Ghana).