Unfortunately, teaching job is undervalued among lot of countries and the salary is poor, until you are not an university teacher/professor. But in this case, at least in the countries I know, you need a PhD (in my current country a postgrad is still enough, but due to the fierce competence, whoever owns a PhD would overcome and get the job). And getting a PhD is very, very shamefully expensive. Even among the studying for free Mercosur countries, education is free only up to degree. And apart of the expenses for fees, books and tuition, it's very desirable you won't work until finishing the PHD, what it's pretty impossible for family men and women who must rely on their salaries to live. You need to have at least a bourgeois family, if not rich, supporting you to study PHD level.