Why would those countries educate the general public to disagree with local power structures, when they mostly just need submissive cheap workforce.

Government educates people when they are a part of the nations money flow. When educated citizens are assets. In your basic banana republic model the people are not part of it. They are just cheap labor for low level jobs, living on scraps. Educating them is down right dangerous for the government. If needed, educated personnel are supplied by foreign actors exploiting the situation.

Poverty and lack of education are forms of control and are not fixed by injecting teachers or money.