No letters after your name are ever going to be a total guarantee of competence any more than they are a guarantee against fraud. Improving competence involves continuing professional development ... That is the really crucial thing, not just passing an examination.
People differ not only in their ability to do but also in their 'will to do'.
Being competent means the ability to control and operate the things in the environment and the environment itself.
The differences between a competent person and an incompetent person are demonstrated in his environment (surroundings).
Competence, like truth, beauty and contact lenses, is in the eye of the beholder.