Here only national championship finalists are allowed to teach - and I think its just in the Amateur catagory. The pros see it as a threat to their income. I think they are short sightted - ams teaching just brings more students into the pool...
Counterpoint: There is an am competitor who teaches newbie classes here. She is a terrible teacher. Both DP and I have taught things other than dance at elementary school through university levels and DP has a masters in adult ed, so we're pretty sure we have a good handle on what constitutes good teaching. Anyway, I question whether this teacher is ultimately doing more harm than good, like driving off newbies who get frustrated, etc.