If you are taking a driving test and you book a test, the examiner won't ask you if you have had any lessons, or how many tests have you taken.
He will assess you on your conduct and competance within your test and your theory knowledge.
Likewise with the NCCA, if a professional carpet cleaner can effectively prove through examination that he or she is competant enough already, then why should it be necessary to make them go on more 'driving lessons' at significant cost in terms of being away from business, lodgings and course fees?
Although I believe that everyone should refresh themselves with a continuation of training, even the older seasoned cleaners (including me).
It is not as straight forward as that. Where would the examination take place for security, and fair play? For arguments sake one organisation employing or franchising could get hold of the test papers and give the answers to all of the others for speed and efficient entry into membership, blow the standards!
I think that it is a good idea in principle but it is not just as easy as that, as high standards have to be maintained in the entry of membership.
I am sure that there would be some way around this, and at one time the NCCA did actually recognise certain other professional organisations training. I believe that some of the standards went down in certain areas and this facility was withdrawn.
Regards
Robert