Interesting questions and discussion. I'm thinking we might learn how measurers are rated in countries where they do that-- maybe Mike Sandford could shed some light, and Bernie too from his international knowledge.
I've always thought our system works pretty well by allowing anyone to measure a course, but always with the "threat" that some experienced measurer may put us to the test by means of a validation measurement. These days I wonder if we actually do enough validations to make that an effective means of enforcing quality.
In the meanwhile we are left with looking at submitted calculations, discussions, and maps. Still, someone who does the math perfectly and produces a good-looking map, may or may not do a great job of measuring the SPR on the course. I always hope that they at least do a "good enough" job of measuring, and I'm confident that measurers who keep at it will to some degree compete with themselves to improve.