The existence of rival exam boards competing for custom means the system is inherently flawed. There is far more at stake than the simple exam fees; when a school adopts a particular syllabus, it will then buy appropriate textbooks and teaching materials (to say nothing of pupils buying past papers and revision guides) and send staff on courses run by the board - all of them nice little earners.
This willingness on the part of both exam boards and teachers to cut corners is an illustration of the way education in this country has been undermined; the undignified scramble to an end result inevitably means compromising the vital process of education and instruction.
It's reminiscent of the rival undertakers in Dave Allen's sketch:
This matter has been written on with more inside knowledge and eloquence than I could ever muster at Going Fast, Getting Nowhere - if you haven't already done so, I urge you to read the post.