A doctor isn't allowed to be a doctor without proper credentials. Neither is a nurse, engineer, accountant etc.
A teacher is more than a warm English body.
I'm a fully trained an accredited teacher across 3 countries and it's bloody insulting to see 'teachers' walking around untrained and think they are better teachers because they THINK they are good at it. There is more to teaching than the warm and fuzzy feeling or making a child happy. Pedagogy, Methodology, Assessment (for learning, of learning), etc. are very important tools of the trade and people who think they can go into the class and get it right are just so darn wrong. No decent school would hire a teacher who isn't trained. How would you know what to write in for the curriculum development of a child. How would you know how to stretch a student? How would you know how to manage the development of a child. It's more than going into the classroom to create a warm and fuzzy feeling. It's more than ABCs or learning basic English. I would NEVER place my child in any situation where FORMAL school and curriculum management is concerned into a school with untrained teachers. Or even a school that doesn't invest in continuous professional development. Ask the principal of your school if s/he'd place his/her child in a school with an untrained teacher... the answer would probably is NOT!
Granted that there are good teachers who aren't certified. There are also a lot of lemons out there in the teaching profession. But when these folks go get their proper certification and seek continual professional development, they usually end up realising how they've gotten it wrong - that anyone can be a teacher - Just stick a person in the classroom and get on the job experience. I'm sure I'll be a great doctor that way too. Get me into a clinic now for on the job training! In X no. years, I can tell a trained doctor that I'm a doctor too as most doctors and nurses learn on the job too!
The QM
Accredited teacher
B.A. (Hons), PGDE, MEd, MAppLing
And continuously fulfills HOURS of professional development each year from local and international institutions/conferences just so that I can be better at my job!