Economics of Simplism, or why some countries are rich and others poor

Why are some countries poor and others rich

“The use of knowledge by one producer does not prevent its use by others. Thus there is no inherent reason that producers in poor countries cannot use the same knowledge as producers in rich countries. If the relevant knowledge is publicly available, poor countries can become rich by having their workers or managers read the appropriate literature. And if the relevant knowledge is proprietary knowledge produced by private R&D, poor countries can become rich by instituting a credible program for respecting foreign firms’ property rights.”
(Romer, David. 2012. Advanced Macroeconomics. New York, NY: McGraw-Hil. p. 144)