(Proverbs 13:23 KJV) Much food is in the tillage of the poor: but there is that is destroyed for want of judgment.That could be interpreted to mean bad decisions by the farmer. It is better in the NASB.
(Proverbs 13:23 NAS77) Abundant food is in the fallow ground of the poor, But it is swept away by injustice.When you have a legal system that caters to those who can afford the long trials and expensive lawyers, common people get pushed out of the picture. Think of a recent Supreme Court decision in Kelo v City of New London. Cities were given the right to condemn any property they want if they think a change will generate more tax revenue for the city. That is not a legal description, it is a common sense observation. Think of the family in Colorado who bought an empty lot in the middle of a development and although it was surrounded by completed houses they were told it was wetlands and fined thousands of dollars a day for disturbing the soil on a lot they had legally bought for building a home.
In a free society people can do well if they are willing to work for it. In Fascism, or crony capitalism as it is sometimes called, those without contacts in government or deep pockets are left in the dust of destitution.
God condemns such actions.
So, yes, oppression is a source of poverty but keep in mind that most of the time it is being pushed by government collusion with big business or just by people in government who want to help you life right.
homo unius libri