That's a good point, but they as all businessmen are looking at it maybe from a money making way. As in their school only has one teaching method so sod it, if anyone comes in here we have to sell this method.
I'm not convinced it even works from a money making point of view - people see through "methods" quickly and boredom sinks in. At least from the Callan/Avalon/whatever method point of view, they all suffer from the same problem in that it's plain boring after a year. I can't figure out why directors would rather have a class full of bored people who can't quit because they've emotionally invested into it than to change things round.
Something I never understood was why schools stick to a single method teaching approach. Ok i understand that it could take training to get a teacher to move from method to another, but with enough practice and help, it can be easily done.
I think most teachers are more than capable to be honest - okay, I couldn't cope if my school moved onto a heavy grammar-based approach, but anything else, I could probably give a bloody good shot.
I guess the complete lack of trust that most directors have for their teachers is part of the problem.
Maybe it's a cultural thing though.