In the United States, each and every child has the ability to get a valuable education, by going through the public school system. This has even been a requirement since the early 1900s. The United States has a philosophy of a right to education, giving children from all walks of life a free education. This unique right can allow children from any walk of life to successfully learn to read and write. All countries, similarly, could adopt a public school system, allowing even the poor to have a chance at success.
Illiteracy is overcome by education. Money can buy better education and tutors, but you still have to learn in order to overcome it. You do not need money to learn or to be literate. You only need the ability to learn, the willingness to learn, and the desire to t to overcome it.