There are three things: training, belonging to a professional organization, being licenced by a government agency.
If I was getting open heart surgery, I'd demand all three.
If I'm buying a new airplane, I'd demand all three.
The Government licence without the professional body runs the risk of paper qualifications without merit. The Professional body without the government licence sets up for internal, incestuous regulation. You could say that the professional organization and the licence confirm the training requirements, but doctors still tend to put their degree on their walls, as well as the others. Where/how you were trained says something other than being licenced by the gov and accepted by peers.
I wouldn't look past a skilled pilot with a suitable background to be employed as a TP, or similiar conditions for an FTE, and I wouldn't demand the ETPS Graduate course for every flight test position, but there are other courses available.
Matthew.