Mr Hay...I believe that you are just restating what I have already said.
No, just stating my point of view, which happens to agree more or less with yours.
Ron, I had a similar experience to yours. I wasn't failed, but I had the distinct impression from the shihan that I should have done much better. Like you, I determined never to repeat such a performance -- and never have.
While I can appreciate the value of your negative testing experience, I would much rather my students benefited from being tested in the way I've described. Personally, I don't believe I've done my job as an instructor if one of my students fails a test (which, to date, has never even come close to happening). If a student of mine wants their next rank, they must go through me to get it. They will have to train before their test like you trained after your failed one in order to be put forward for testing. If they can satisfy me, they will satisfy our shihan. This saves Kawahara sensei the embarrassment of failing a student, it saves the student the embarrassment of failing, and it saves me the shame of causing so much embarrassment to both shihan and student.
Best to you, too.