CELTA can be done by non-natives which is also a bit controversial in a sense. When I watched the French and Austrian teachers teach, I could hear many mistakes which could be problematic. What if they entered a school which required them to teach 'a' and 'the'?
Well, I suppose it could be argued that the main aim of the CELTA is to familiarise a complete beginner with the principles of planning lessons / entertaining children rather than being a language assessment per se but yes, you do wonder what exactly your role in the classroom is when being a competent user of the language isn't really important...
Go to an IATEFL conference and see all the middle-aged Polish women who teach English and try to talk to them
I try not to {shudders] but to be fair to them they are usually the victims of pretty bad teaching courses from possibly 30 years ago. Things have possibly moved on a little since they got their qualifications but they usually haven't continued their training since they graduated - apart from sitting at the back of a sweaty IATEFL lecture theatre once a year, waiting for the handouts at the end. IATEFL's just a marketing exercise for the publishes anyway...