Ever thought about what is the #1 problem all countries face? I searched and multiple sources said that an economy's number one problem is scarcity. There is an unlimited demand from humans but there are only limited resources. It becomes now a problem when the government has to answer these questions:
1. What to produce?
2. How to produce?
3. Whom to distribute the product?
With limited resources, the government has to decide on the most profitable product to make. They have to find a way where they minimize the costs but maximize the profit. But then they have to ask themselves who should benefit from the end product? Some government decide based on wealth. If you are rich, you get the best products or services. Some governments distribute it equally or based on needs but this usually happens in totalitarian authorities. Some governments mix it up and give some to those in need but also to those who pay taxes the highest.
There is a lot of reasons why this problem can't be solved for good. One is that there will always be needs from people. The population keeps growing and growing. The resources keeps on dwindling down. Not to mention corruption. Will there be a time where we would all have to literally fight for resources?
While this is true, resources are limited, and the real problem lies in using these limited resources effectively. You mentioned corruption, and I believe this is where the first problem begins. Then there's the income distribution and improper distribution.
Many sources may have said it because of those who want to call it a scarcity, and yes, scarcity is a problem, but we shouldn't attribute the global economic downturn to it. With sustainable production and consumption, these problems wouldn't exist, but leaders don't want that.