Standardisation is a big issue.
In the Bad Old Days, the Department of Civil Aviation (pre-DoTA, CAA, CASA) had Examiners of Airmen, and they were the only ones allowed to issue licences and instructor ratings, instrument ratings etc. They worked for the Gummint, and supposedly all sang from the same sheet of music.
Then as things changed, the testing role was devolved in part to the industry and Approved Testing Officers were created to lighten CASA's load. That was where the divergence of standards really accelerated. It is now possible for an ATO to be working in a school which he owns, and in which he was taught himself, and outside of which he has never worked.
It is in his interests to have as many of his own students graduate to help his statistics along. He teaches his students, who become instructors and pass on the skinny knowledge which becomes skinnier and skinnier with each generation. No outside cross-fertilisation occurs. Not good.
