Some people have more brain or brawn than others. Some have invested time and money in education and training to develop special skills that earn high salaries. In general, the greater the education, the higher the income. Finally, income inequality is often the result of discrimination . Blacks and hispanics tend to have the lowest incomes, while white non-hispanics and Asians tend to have the highest incomes.
Females tend to earn much less than males.
Redressing discrimination problems generally involves changing laws and the social conscience.