Like, none of what you wrote here has nothing whatsoever with the actual concrete practice test this particular guitarist complained about. Testing scales does not test any of these, actually. It is just absurd to claim that playing scales at practice test is done in order to test how you play "something you have rehearsed accurately" or "ability to transpose".

> If you're as good at sight-reading as you say, you can just read the scales off the sheet music and play them all perfectly the first time, so what's the problem?

So basically, you do not know anything about the test the guitarist complained about.