Start with something simple, say taxing people of one race 15% more than another race. That would seem a valid form of repression.

Okay, so that rarely happens and is almost always combined with far greater forms of repression. But there are less extreme examples. What about taxing someone more when they have kids, or more when they don't?

Sin taxes also seems a way to repress certain behaviors in society by increasing their cost. Why can't the logic apply in other areas of life where tax rates are unequal?

What are the penalties for carrying bullion?