In the US income tax is progressive but only a portion of the tax structure. The biggest factor is that capital gains are taxed at a much lower rate than earned

In the US income tax is progressive but only a portion of the tax structure. The biggest factor is that capital gains are taxed at a much lower rate than earned income. (income from selling labor) There are also a number of flat amount / percent taxes, many of which vary by state. Finally, the tax structure is sufficiently complicated that those who can afford skilled accountants can further lower their paid taxes considerably through tricks and loopholes.