Deepening Income Inequality

As we all know, income inequality is growing more and more common nowadays. Because of disabilities, age and gender. Why do people treat their co-workers differently? Is it because of their physical appearances? I think that income inequality is inequitable because everyone should be treated with equality and also disability discrimination is against the law for some countries. How do you know what someone is capable of if you don't give them a chance? What do you think of this topic?